Process for the disposal and recovery of phossy water

Phossy water is a toxic liquid waste that is generated when elemental phosphorus is manufactured, stored, or processed into phosphorus-containing products. Elemental phosphorus may be present as a solution, as colloidal particles, and as settleable particles. The primary objects of the invention are as follows: PA0 1. To provide a process for the disposal of phossy water stored at the TVA National Fertilizer and Environmental Research Center. PA0 2. To provide a process for the recovery of phossy water that will be generated when hazardous wastes stored at the TVA National Fertilizer and Environmental Research Center are recycled. Phossy water can be disposed of by using it to quench and granulate molten slag at electric furnaces used to manufacture elemental phosphorus. The elemental phosphorus content of the phossy water is limited to about 2 parts per million. Phossy water that will be generated during recycling of hazardous wastes can be recovered by using it in the process to produce fluid fertilizers, Phossy water is used instead of process water to manufacture fluid fertilizers. The elemental phosphorus content of the phossy water is not limited to 2 parts per million.

BACKGROUND OF THE INVENTION 
Accumulation of Hazardous Wastes at the TVA National Fertilizer and 
Environmental Research Center 
When water comes in intimate contact with elemental phosphorus, the 
elemental phosphorus becomes a constituent of the water in one or more of 
the following forms. 
1. Elemental phosphorus dissolves in water. When water is saturated with 
elemental phosphorus at room temperature the water will contain about 30 
parts per billion of elemental phosphorus. 
2. Colloidal phosphorus particles become suspended in water. 
3. Settleable phosphorus particles become suspended in water. 
Water that contains elemental phosphorus in any one of the three forms is 
commonly called "phossy water." 
It is not feasible to avoid the generation of phossy water during the 
manufacture of elemental phosphorus, .during its storage, and during its 
processing to make phosphorus chemicals. Nevertheless, elemental 
phosphorus is a highly toxic chemical, and release of phossy water as a 
liquid waste is a serious threat to marine life. 
Late in 1969 a number of massive fishkills occurred in Long Harbour and 
neighboring regions of Placentia Bay in Newfoundland. The fishkills were 
attributed to the startup of a phosphorus producing plant at Long Harbour. 
A study was undertaken by the Fisheries Research Board of Canada to 
determine the toxicity of yellow phosphorus to marine life. Results of the 
research were reported in a book entitled "Effects of Elemental Phosphorus 
on Marine Life," compiled and edited by P. J. Jangaard, Circular No. 2, 
November 1972, Atlantic Regional Office, Research and Development, 
Fisheries Research Board of Canada, Halifax, Nova Scotia. 
The book is a compilation of technical papers which describe the pollution 
problem at Long Harbour, give results of research on toxicity of elemental 
phosphorus and describe methods used to clean up Placentia Bay. An 
abstract of one of the technical papers is given below as an example to 
show the relative sensitivity of marine life to small concentrations of 
elemental phosphorus in water. The paper abstracted is "Yellow Phosphorus 
Pollution.: Its Toxicity to Seawater-Maintained Brook Trout (Salvelinus 
fontinalis) and smelt (Osmerus mordax)," by G. L Fletcher, R. J. Hoyle, 
and D. A. Horne, Fisheries Research Board of Canada, Halifax Laboratory, 
Halifax, Nova Scotia. 
Yellow phosphorus was lethal, to seawater-maintained brook trout and smelt 
at concentrations as low as 0.5 .mu.g/liter. Trout that were exposed to 
low concentrations of yellow phosphorus (0.5 and 7.0 .mu.g/liter) for 50 
or more hours turned red and showed signs of extensive hemolysis. At 
death, all trout that had, been exposed to 104 .mu.g/liter. yellow 
phosphorus and lower had hematocrits that were significantly lower than 
those of the controls. 
Other species of marine life exhibited similar sensitivity to very small, 
concentrations of elemental phosphorus in water, It is evident that wastes 
containing any measurable concentration of elemental phosphorus may be a 
threat to the environment. And by means of chromotography, elemental 
phosphorus can be detected in water at concentrations as low as 0.5 
.mu.g/liter (0.5 part per billion.). 
Elemental phosphorus was produced commercially at a federal facility now 
known as the National Fertilizer and Environmental Research. Center 
(NFERC) at Muscle Shoals, Ala. NFERC is operated by the Tennessee Valley 
Authority (TVA). Production of elemental phosphorus began at NFERC in 1934 
and its production was discontinued in 1976. 
Much water is used in the manufacture of elemental phosphorus and this 
results in the generation of phossy water. Elemental phosphorus is 
produced by smelting a mixture of phosphate ore, reducing carbon, and 
silica in electric furnaces. The element leaves the furnace in a gas 
mixture. The gases are then cooled by contacting them with a circulating 
stream of water, and elemental phosphorus condenses as a liquid. From this 
contact between water and elemental phosphorus the water will contain 
elemental phosphorus in all three forms discussed above. 
Part of the elemental phosphorus is condensed as an emulsion called. 
phosphorus sludge which is comprised of dirt, water, and droplets of 
liquid phosphorus. Although the composition of phosphorus sludge varies 
widely, the freshly formed emulsion contains approximately equal 
percentages of dirt, water, and elemental phosphorus. Processes are 
available for separating elemental phosphorus from impurities in 
phosphorus sludge, but it has not been feasible to remove all the 
phosphorus from the dirt and water. Residue from the various recovery 
processes contains enough elemental phosphorus for the residue to be a 
toxic waste. Water is used in the recovery processes and phossy water is 
generated. For example, elemental phosphorus may be separated from the 
impurities by distillation in which case phosphorus vapor and water vapor 
will be condensed by contacting gases with water. 
Gases from, the electric furnace contain particulates. Ellectrostatic 
precipitators were used at NFERC to remove the particulates and thereby 
decrease the quantity of phosphorus sludge that was made. However, 
particulates were not completely removed from the gas, and the quantity of 
phosphorus sludge formed during the condensation of elemental phosphorus 
was reduced but was not eliminated. Particulates removed from the furnace 
gas are called precipitator dust. 
Precipitator dust is comprised of very small particles. Furnace gases, 
including elemental phosphorus, adsorb on the surfaces of the particulates 
and the precipitator dust thereby contains elemental phosphorus. 
When elemental phosphorus was being produced at NFERC, phossy water and 
phosphorus sludge were discharged into a 14-acre settling pond. FIG. 1 is 
an aerial view of the settling pond. Also, phospborus-containing wastes 
were deposited in other ponds, in sumps, and in tanks. Elemental 
phosphorus was used as a munition during World War II and during the 
Korean armed conflict. Munitions-grade elemental phosphorus called for 
almost complete removal of phosphorus sludge from the element, and this 
was achieved by washing phosphorus with hot water in a vertical tank. The 
lower density phosphorus sludge floated on top of the liquid phosphorus 
and separated by overflowing the tank. The phosphorus sludge contained a 
substantial amount of elemental phosphorus. During wartime emergencies, 
production of munitions-grade elemental phosphorus took precedence over 
phosphorus recovery efficiency. The washings containing elemental 
phosphorus, phosphorus sludge, and phossy water were discharged into the 
settling pond, along with phossy water from the phosphorus condensers. 
Phossy water was clarified in the pond to separate suspended phosphorus 
particles. Also, phossy water was diluted with cooling water. After 
settling and dilution, phossy water was discharged into a stream (Pond 
Creek) as a waste. The average elemental phosphorus content of the waste 
phossy water was about 90 parts per billion parts of water, but the waste 
frequently contained higher concentrations. 
The quantity of phosphorus sludge deposited in the settling pond (FIG. 1) 
increased rapidly when phosphorus was being washed. The pond was not lined 
with an impervious membrane and leakages caused fishkills. In 1980 about 
half of the 14-acre settling pond was filled in with ash and phosphate ore 
as shown in FIG. 2. The quantity of elemental phosphorus buried in the 
pond is not known with accuracy. It is assumed about 3 percent of the 
elemental phosphorus produced was lost in the phosphorus sludge. Since 
about 1.1 million tons of elemental phosphorus was produced, elemental, 
phosphorus in sludge will be as follows: 
##EQU1## 
However, the quantity may be greater than 34,000 tons. 
FIG. 3 shows the part of the settling pond that was not filled in. The 
liquid in the unfilled-in part of the pond is phossy water containing 
dissolved elemental phosphorus, colloidal phosphorus particles, and 
possibly some settleable phosphorus particles. 
The original volume of the 14-acre settling pond was 2,300,000 cubic feet 
as reported in "Waste Effluent; Treatment and Reuse," Chemical Engineering 
Progress, volume 65, June 1969. Under the assumption that half the pond 
was unfilled-in, the volume of phossy water is estimated to be 1,150,000 
cubic feet. 
Precipitator dust was generated at NFERC at a rate of 0.06 ton (dry basis) 
per ton elemental phosphorus produced. Since over 1.1 million tons of 
phosphorus was produced at NFERC, simple calculations indicate about 
68,000 tons of precipitator dust was generated. However, precipitators 
were installed about four years after production of elemental phosphorus 
was undertaken. Some precipitator dust was distributed as fertilizer 
during World War II. Too, small particles comprising precipitator dust 
adsorb water in outside storage and this increases the quantity. Taking 
these factors into consideration, it was estimated about 34,000 tons of 
precipitator dust (wet basis) is stored at NFERC. 
When precipitator dust was collected the average elemental phosphorus 
content was about 0.3 percent. But the elemental phosphorus content may be 
as high as 2.1 percent. 
Processes have been invented to recover phosphorus sludge by a combination 
of distillation and recycle. The phosphorus sludge is distilled to recover 
most of the elemental, phosphorus. Phossy water will be generated when the 
phosphorus is condensed. In accordance with U.S. Pat. No. 4,608,241, 
residue from distillation may be agglomerated by tumbling with a binder 
formed by reacting acidic phosphorus compounds with alkaline substances to 
prepare feedstock for phosphorus furnaces. When the feedstock is smelted, 
elemental phosphorus is produced. 
U.S. Pat. No. 4,968,499 discloses a process for converting precipitator 
dust into phosphorus furnace feedstock whereby the waste is agglomerated 
by a process similar to that used to agglomerate residue from distillation 
of phosphorus sludge. Elemental phosphorus present in the precipitator 
dust will be vaporized when agglomerates are dried. Scrubbing the gas with 
water for pollution abatement will condense the phosphorus and this will 
generate phossy water. 
Processes were invented to recover phossy water generated during 
condensation of elemental phosphorus as disclosed in U.S. Pat. Nos. 
4,383,847; 4,451,277; and 4,537,615. Phossy water is used instead of 
process water to manufacture fluid fertilizers. 
A process is needed to dispose of the large volume of phossy water shown in 
FIG. 3. The quantity is too much for recovery in fluid fertilizers as 
disclosed in U.S. Pat. Nos. 4,383,847; 4,451,277; and 4,537,615. Since the 
elemental phosphorus content is largely limited to dissolved phosphorus 
and colloidal phosphorus, evaporation to dryness appeared to be the 
preferred disposal method. And a suitable source of heat energy is needed 
to evaporate the phossy water. 
Phossy water generated when phosphorus is condensed contains dissolved 
phosphorus, colloidal phosphorus particles, and settleable phosphorus 
particles. Although phossy water may be clarified to remove settleable 
phosphorus particles, industrial clarification processes do not remove all 
suspended particles. Phosphoric acid accumulates in water recirculated at 
phosphorus condensers, and the phosphoric acid is neutralized with ammonia 
forming ammonium phosphate. Thus phossy water bled off from the 
recirculating stream of condenser water contains the nutrients, nitrogen 
and P.sub.2 O.sub.5. The nutrients are recovered when the phossy water is 
added to fluid fertilizers as described in U.S. Pat. Nos. 4,383,847; 
4,451,277; and 4,537,615. 
Phossy water from phosphorus condensing contains ammonium fluosilicate, 
potassium fluosilicate, and sodium fluosilicate. Although the 
concentration of the various salts, including ammonium phosphate, can be 
increased by recirculating condenser water, fluosilicate salts precipitate 
as scales on heat transfer surfaces, in pumps, and in piping. Thus the 
concentration of the salts has to be limited to prevent precipitation of 
fluosilicates. A phosphorus condensing system is needed which will permit 
salts in the recirculating condenser water to be concentrated. 
SUMMARY AND OBJECTS OF THE INVENTION 
When TVA undertook production of elemental phosphorus in 1934 the process 
was incompletely developed. The agency proceeded to complete the 
development and simultaneously produce the chemical on a large-scale 
basis. Much innovative technology was developed and demonstrated at NFERC. 
The NFERC became the center for technology on production of elemental 
phosphorus. 
Wastes which contained elemental phosphorus were generated at NFERC at the 
beginning of the large-scale operation. However, it was not known that 
elemental phosphorus was so toxic and the primary concern was to obtain 
sustained operation of the production facilities. During World War II 
elemental phosphorus produced at NFERC was used as a munition, and meeting 
production schedules became even more important. Work on recovery of 
wastes was not of primary importance during the wartime emergency. 
After World War II the program at NFERC shifted back to production of 
elemental phosphorus for use in the development of new and improved 
fertilizers. Losses of elemental phosphorus in wastes was of greater 
concern because of the need to achieve high recoveries. Although toxicity 
of elemental phosphorus became evident, treatment of elemental 
phosphorus-containing wastes had to be economically justified on the basis 
of improved efficiency. The discharge of phossy water into surface streams 
was considered acceptable after settleable phosphorus particles were 
removed by clarification in a large settling pond such as the one shown in 
FIG. 1. 
In the late 1950s and 1960s environmental regulations began to emerge. At 
NFERC, innovative processes were provided to decrease emissions of 
pollutants in air and decrease discharges of pollutants into surface 
streams. Phossy water generated during the condensation of elemental 
phosphorus was clarified to remove most of the suspended sludge, and the 
clarified phossy water was recycled to the condensing system. Insoluble 
fluorine compounds accumulated in the recycled phossy water and it was 
necessary to bleed off a stream of the clarified phossy water and replace 
it with process water to prevent precipitation of fluorine compounds. The 
bled phossy water was diluted with cooling water and further clarified in 
the settling pond. With this improvement the average elemental phosphorus 
content of phossy water was reduced and the rate of deposition of 
phosphorus sludge in the settling pond was lessened. 
The Fisheries Research Board of Canada reported in the 1970s that some 
species of marine life are killed by concentrations of elemental 
phosphorus as low as a few parts per billion. Effluent from the settling 
pond had little or no settleable particles of elemental phosphorus, 
Nevertheless, the normal elemental phosphorus content was about 90 parts 
per billion, and the concentration was significantly greater than this 
when the pond became more heavily loaded with suspended particles. The 
effluent obviously was too toxic to be released to surface streams. 
Research and development on the process for producing elemental phosphorus 
was being phased out in the 1970s. There was little incentive to work on 
processes for correcting the phossy water problem and when production was 
discontinued in 1976, discharge of the waste was an uncorrected 
environmental problem. 
A program of investigation was undertaken by James C. Barber and 
Associates, Inc. to devise practical means of utilizing phossy water that 
remained at NFERC. Results of research and development at NFERC on 
elemental phosphorus production and on fertilizers provided a basis for 
inventions to utilize phossy water from an operating plant. However, 
phossy water in the settling pond shown in FIG. 3 has little potential for 
utility. 
The primary objects of the present invention, therefore, are as follows. 
1. To provide a process for the disposal of phossy water when the phossy 
water contains little or no settleable particles of elemental phosphorus. 
2. To provide a process for the recovery of phossy water when the phossy 
water contains dissolved elemental phosphorus, colloidal particles of 
elemental phosphorus, and settleable particles of elemental phosphorus.

DESCRIPTION OF PHOTOGRAPHS AND DRAWINGS 
FIG. 1 is an aerial photograph of a 14-acre settling pond that was formerly 
used as a depository for phosphorus sludge. Phossy water continuously 
discharged through a weir into a ditch and the ditch discharged into a 
stream called Pond Creek. Pond Creek discharged into the Tennessee River. 
While phossy water was being discharged from the settling pond, Pond Creek 
would not sustain marine life. 
The settling pond shown in FIG. 1 was constructed in 1936 soon after 
production of elemental phosphorus was started at NFERC. At this time 
lining of the pond with a sheet of plastic was not practiced because 
plastic sheets were not available. Much of the pond was filled in by 
phosphorus sludge, particularly during wartime emergencies when elemental 
phosphorus was being washed to make munitions. In 1976 when production of 
elemental phosphorus was discontinued the pond area was estimated to be 10 
acres. 
In 1980 part of the settling pond shown in FIG. 1 was filled in with ash 
and phosphate ore. FIG. 2 is a photograph showing material in the settling 
pond being buried. 
FIG. 3 is a photograph of the part of the settling pond that was not filled 
in. Liquid shown in FIG. 3 is phossy water. From examination of FIGS. 1 
and 3 it appears about half of the settling pond was filled in. The volume 
of phossy water was estimated to be 1,150,000 cubic feet. An analysis of 
the phossy water is not available, but phossy water discharging from the 
settling pond had an average elemental phosphorus content of about 0.09 
part per million. After extended settling in the pond, elemental 
phosphorus will be present primarily as dissolved phosphorus and colloidal 
particles. 
FIG. 4 is a diagram to show how phossy water can be disposed of by 
utilizing waste energy generated during the production of elemental 
phosphorus. Phossy water 1 is transported from settling pond 2, such as 
the settling pond shown in FIG. 3, to reservoir 3 located near a 
phosphorus production facility. 
Silica 4, phosphorus-containing solid 5, and reducing carbon 6 are smelted 
in electric furnace 7. Molten slag 8 flows from electric furnace 7 to 
quenching 9. Molten slag is quenched with phossy water 1 to form 
granulated slag 10. Phossy water 1 is vaporized by contact with molten 
slag to form steam 11. 
Furnace gas 12, consisting mainly of carbon monoxide, phosphorus vapor and 
hydrogen, flows to condenser 13 wherein gas is cooled and elemental 
phosphorus condenses. Phosphorus sludge 14 is transported to a facility to 
separate elemental phosphorus from the impurities. This facility is not 
shown in FIG. 4. 
Noncondensable gas 15 consisting of carbon monoxide and hydrogen is a 
byproduct which can be used as a fuel. Elemental phosphorus 16 is the 
product. 
FIG. 5 is a block diagram illustrating the process for the recovery 
of-phossy water in fluid fertilizers. Phosphate ore 17 and residue 23 from 
distillation of underflow 21, comprise phosphorus-containing solids 5. 
Phosphorus-containing solids 5, silica 4, and reducing carbon 6 are 
smelted in electric furnace 7. Furnace gas 12 flows to condenser 13 where 
gases are cooled by recirculating phossy water. Recirculating equipment is 
not shown in FIG. 5. Noncondensable gas 15 consisting of carbon monoxide 
and hydrogen is a byproduct which can be used as a fuel. Phosphorus sludge 
14 is transported to a facility to separate elemental phosphorus from the 
impurities. This facility is not shown in FIG. 5. Elemental phosphorus 16 
is the product from smelting phosphorus-containing solids. 
A stream of phossy water 1 is bled from recirculating equipment at 
condenser 13 and is transported to ammoniator 18. Ammonia 19 is added to 
ammoniator 18 to increase pH of phossy water 1 to the range of 8.5 to 9.0. 
Fluosilicate salts are converted to fluoride salts with precipitation of 
silica in accordance with the following equation. 
EQU (NH.sub.4).sub.2 SiF.sub.6 +4NH.sub.3 +2H.sub.2 O=6NH.sub.4 F+SiO.sub.2. 
Phossy water 1 from condenser 13 contains ammonium fluosilicate, sodium 
fluosilicate, and potassium fluosilicate. Sodium and potassium 
fluosilicates are derived from volatilization of sodium and potassium 
compounds from electric furnace 7. These alkali metal compounds react with 
fluosilicic acid to form fluosilicate salts, which then react with ammonia 
to form alkali metal fluorides and ammonium fluoride by reactions similar 
to that shown above. Silica is precipitated when fluosilicate salts are 
ammoniated. 
Precipitator dust that has accumulated at NFERC is converted into 
phosphorus furnace feedstock in accordance with U.S. Pat. No. 4,968,499. 
The precipitator dust is agglomerated and the agglomerates are indurated 
in the temperature range of 220.degree. to 1832.degree. degrees F. The 
facility to convert precipitator dust into phosphorus furnace feedstock is 
not shown in FIG. 5. Phossy water is generated when gases from the 
indurator are scrubbed with water. The phossy water generated is mixed 
with ammoniated phossy water 1 from ammoniator 18. 
The mixture of phossy water flows to clarifier 20. Overflow from clarifier 
20 is clarified phossy water 1. Underflow 21 from clarifier 20 flows to 
still. 22. Underflow 21 is distilled to obtain elemental phosphorus 16 and 
residue 23. Residue 23 is smelted in electric furnace 7. 
Phossy water 1 from clarifier 20 is added to recirculating phossy water at 
condenser 13. Noncondensable gases 15 are comprised primarily of-carbon 
monoxide and hydrogen and they are used as a fuel. 
A stream of phossy water 1 is bled off and added to neutralizer 24. Ammonia 
19, phosphoric acid 25, and suspending clay 26 are added to neutralizer 24 
to make fluid fertilizer 27. 
FIG. 6 is a diagram of equipment used to quench the slag at NFERC. Molten 
slag 8 was tapped from electric furnace 7 into slag runner 28. Molten slag 
8 flowed into sluiceway 29. As molten slag 8 dropped into sluiceway 29 it 
was contacted by water discharging from a battery of granulating nozzles 
30. Molten slag 8 was solidified and simultaneously granulated by the jets 
of high-velocity water. Three batteries of transporting nozzles 31 sluiced 
the resulting slurry of granulated slag and water to a pit where water was 
separated from the solid. Water was recycled to granulate and transport 
slurry of slag and water to the slag pit. The slag pit is not shown in 
FIG. 6. Sluiceway 29 was 110 feet long. 
Four centrifugal pumps, each having a rated capacity of 800 gallons per 
minute at 300-foot head, supplied water for the nozzles. The pumps are not 
shown in FIG. 6. Water was supplied through 8-inch water supply pipe 32. 
Sluiceway 29 was lined with brick 33 set in concrete 34. Red shale brick 
were used to line the sluiceway. The concrete was reinforced. 
PRIOR ART 
U.S. Pat. No. 4,383,847 is a process for the production of fluid 
fertilizer. The following patents were cited as prior art, and these 
patents are referred to as prior art for the present patent application. 
1. U.S. Pat. No. 2,040,081, Harry A. Curtis, Mar. 12, 1936. 
2. U.S. Pat. No. 2,741,545, F. T, Nielsson, Apr. 10, 1956. 
3. U.S. Pat. No. 3,012,874, A. B. Phillips, et al., Dec. 12, 1961. 
4. U.S. Pat. No. 3,034,883, T. P. Hignett, et al., May 15, 1962. 
5. U.S. Pat. No. 3,113,858, A. V. Slack, et al., Dec. 10, 1963. 
6. U.S. Pat. No. 3,177,062, T. P. Hignett, et al., Apr. 6, 1965. 
7. U.S. Pat. No. 3,202,744, J. C. Barber, et al., Aug. 24, 1965. 
8. U.S. Pat. No. 3,335,094, W. J. Darby, Aug. 8, 1967. 
9. U.S. Pat. No. 3,464,809, G. Hicks, Sep. 2, 1969. 
10. U.S. Pat. No. 3,813,233, L. A. Kendrick, Jr., May 28, 1974. 
U.S. Pat. No. 4,451,277 discloses another process for the production of 
fluid fertilizer. The following publications and patents were cited as 
prior art, and this prior art is referred to herein. 
1. Chemical Engineering Progress, Vol. 65, No. 6, June 1969, "Waste 
Effluent; Treatment and Reuse," J. C. Barber. 
2. U.S. Pat. No. 2,039,297, H. A. Curtis, May 5, 1936. 
3. U.S. Pat. No. 2,135,486, L. H. Almond, Nov. 8, 1938. 
4. U.S. Pat. No. 3,084,029, J. C. Barber, G. H. Megar, and T. S. Sloan, 
Apr. 2, 1963. 
5. U.S. Pat. No. 3,113,839, J. C. Barber, G. H. Megar, and T. S. Sloan, 
Dec. 10, 1963. 
6. U.S. Pat. No. 3,136,604, J. C. Barber, G. H. Megar, and T. S. Sloan, 
Jun. 9, 1964. 
7. U.S. Pat. No. 3,428,430, G. H. Megar and Arnett Hendrix, Feb. 18, 1969. 
8. U.S. Pat. No. 3,531,250, Arnulf Hinz, et al., Sep. 29, 1970. 
9. U.S. Pat. No. 3,433,601, H. M. Stevens, Mar. 18, 1969. 
10. U.S. Pat. No. 3,615,218, L. B. Post, R. E. Paul, and W. R. Crudup, Oct. 
26, 1971. 
11. U.S. Pat. No. 4,081,333, W. S. Holmes, E. J. Lowe, and E. R. Brazier, 
Mar. 28, 1978. 
12. U.S. Pat. No. 3,684,461, Fritz Muller, Karl-Heinz Stendback, and 
Horst-Heinrich Weizenkorn, Aug. 15, 1972. 
13. U.S. Pat. No. 3,436,184, J. A. Hinkebein, Apr. 1, 1969. 
14. U.S. Pat. No. 3,515,515, J. A. Hinkebein, Jun. 2, 1979. 
15. U.S. Pat. No. 3,743,700, C. P. Orr, Jul. 3, 1973. 
16. U.S. Pat. No. 3,852,050, Chao Hsiao and L. B. Horton, Dec. 3, 1974. 
17. Proceedings of the 35th Industrial Waste Conference, Purdue University, 
May 13, 14, and 15, 1980, "Development of a Wastewater Management System 
for an Elemental. Phosphorus Production Plant," John H. Koon, Gary M. 
Davis, Paul D. Knowlson, and Edward F. Smith. 
A further literature search was undertaken for prior art reported over the 
period 1980 to present. The Chemical Abstracts Search Service was 
requested to search the literature for accumulations, utilization, and 
disposal of water containing elemental phosphorus. Although a computer 
search of the literature identified 90 references, 16 references reported 
prior art relating to the subject of the present application. The 16 
references and abstracts are given below. 
1. "Development of a Wastewater Management System for an Elemental 
Phosphorus Production Plant," John H. Koon, Gary M. Davis, Paul D. 
Knowlson, and Edward F. Smith, Proceedings of the Industrial Waste 
Conference, volume date 1980, 35, 550-9, publication year 1981. A pilot 
plant system of chemical precipitation, granular media filtration, and 
activated carbon adsorption was effective in removing phosphorus and in 
reducing F.sup.- and PO.sub.4.sup..tbd. concentrations in phosphorus and 
phosphoric acid manufacture wastewater. 
2. "Removing Elemental Phosphorus from Wastewaters," Clark Bennett and 
Theodore T. Garrett, German patent 3,046,898, Sep. 3, 1981. An aeration 
stage, following the precipitation of (PO.sub.4).sup..tbd. from phosphorus 
production wastewaters and prior to sedimentation and filtration, reduced 
phosphorus to nondetectable levels, whereas post-treatment with activated: 
carbon left traces of phosphorus in the effluent. Thus precipitation with 
CaO and aeration for 45 minutes with an air:water volume ratio of 2, 
minimum, reduced phosphorus levels from 244 parts per billion to 
nondetectable. 
3. "Treatment of Wastewaters Containing Phosphorus," Herbert Diskowski, 
Johannes Krause, and Dietrich Mandelkow, European patent 49,762, Apr. 21, 
1982. The treatment of wastewater from electrothermal production of 
phosphorus includes centrifugal filtration, of the wastewater at 
&gt;46.degree. and pH 0.5-4.0, the separation of the filtrate into yellow 
phosphorus and water layers in a settling tank for 10-60 minutes, 
oxidation of the supernatant from the settling tank, and neutralization of 
the phosphorus-free wastewater. Thus the wastewater at 55.degree. and pH 
2-3 is filtered and the filtrate containing 290 mg. phosphorus per liter 
is allowed to stand in the settling tank for 30 minutes. A bleaching 
liquor 200 liters containing 14 percent NaOC1 is added to 50 cubic meters 
of the supernatant containing 25 micrograms of phosphorus per liter 
resulting in water with phosphorus content &gt;1 milogram per liter. 
4. "Purification of Water Containing Phosphorus," Doris Gisbier, Dietman 
Zobel, Herbert Soyka, Heinz Rathmann, and Renate Rust, East German patent 
153,803, Feb. 3, 1982. 
Elemental yellow phosphorus is removed from phosphorus storage and rinsing 
wastewaters by treatment with alkaline wastewaters from production of 
K.sub.4 Fe(CN).sub.6. Thus, a wastewater at pH 5.6 containing elemental 
phosphorus 40 and P.sub.2 O.sub.5 (after oxidation) 307 milograms per 
liter was mixed with ferrocyanide-production wastewater at pH 11.7 
containing CN-45 milograms per liter and filterable solids 105 grams per 
liter in a 1:1 ratio at 38.degree., which after settling produced an 
effluent of pH 11.5 containing P.sub.2 O.sub.5 (after oxidation) 0.0021 
percent. No PH.sub.3 or P.sub.2 O.sub.5 fumes were formed. 
5. "Energy Conservation and Pollution Abatement at Phosphorus Furnaces," 
James C. Barber, U.S. Pat. No. 4,372,929, Feb. 8, 1983. 
Coke fines are blended with acidic waste material from phosphorus 
electrothermal manufacture to be agglomerated to form particles for use in 
a phosphorus furnace. Flotation tailings from phosphate rock beneficiation 
(mainly quartz) and a phosphate concentrate are agglomerated to prepare a 
self-fluxing furnace charge. Phosphate and coke fines are agglomerated to 
give particles with matched sizes to increase the output of the phosphorus 
furnace. The bleedoff water from condensing gaseous phosphorus from the 
furnace is used as feedstock for making suspension fertilizers. The sludge 
acid that separates from post-precipitation of impurities in wet-process 
H.sub.3 PO.sub.4 is used as a binder in preparing agglomerates. The 
apparatuses are described for agglomerating coke and phosphate and for 
measuring the abrasion and shatter resistance of the agglomerates. 
6. "Recovery of Phosphorus from Sludge," George James Morgan, European 
patent 98,038, Jan. 11, 1984. 
Elemental phosphorus is recovered from the sludge formed during the 
production of phosphorus by smelting of phosphate rock. The water from the 
sludge is removed by evaporation using a heat-transfer medium and, the 
phosphorus values are separated from the solid impurities contained in the 
sludge by known techniques such as centrifuging, filtering, settling, etc. 
Heated phosphorus is utilized as the direct heat-transfer fluid in the 
process, which eliminates the fouling and scaling problems associated with 
indirect heat-transfer means. 
7. "Fluid Fertilizer from a Phosphorus Furnace Waste Stream," James C. 
Barber, U.S. Pat. No. 4,451,277, May 29, 1984. 
Fluid fertilizer is produced by adding wastewater from a phosphorus 
smelting furnace to the first-stage ammoniator in an orthophosphate 
suspension fertilizer process. Phosphate ore, reducing carbon, and silica 
rock are smelted, and the phosphorus-containing gas evolved is treated to 
remove suspended dust, then cooled in an adiabatic condenser wherein water 
is (1) sprayed into the condenser to condense phosphorus from the gas, (2) 
collected in a sump, and (3) recirculated to the condenser. Alkaline 
material (to maintain a pH of 5.5 to 6.0) and fresh water are added to the 
recirculating stream, and water is bled off from this stream and clarified 
for use in fertilizer manufacture. A process is disclosed also for 
production of H.sub.3 PO.sub.4 of high purity, suitable as animal feed. 
The technology provides environmentally acceptable disposal means for 
aqueous wastes containing elemental phosphorus, at a favorable cost. Thus, 
a mixture of rock phosphate, silica rock, and coke was smelted, the 
furnace gas was treated in an electrostatic precipitator, and the gas was 
cooled in an adiabatic condenser. A water-cooled coil was inserted in the 
condenser sump, and, makeup water was added. The condenser water was 
neutralized with soda ash (.about.438 pounds per ton of phosphorus 
produced). Water (containing .about.0.2% P.sub.2 O.sub.5) was bled off at 
6500 pounds per ton phosphorus produced, and suspension fertilizer was 
produced at 37,100 pounds per ton of elemental phosphorus produced. 
8. "Treatment of Phosphorus-Containing Waste Material, David L. Dodson, 
Bruce D. Pate, Phillip C. Rogers, U.S. Pat. No. 4,481,176, Nov. 6, 1984. 
Elemental phosphorus values are recovered from phosphorus-containing waste 
materials. The size of the solid particulate materials of the sludge is 
decreased and a uniform homogeneous sludge is formed which is filtered 
through a high-pressure thin-cake filter resulting in a filtrate high in 
phosphorus values. A pump retrieval means is described for retrieving the 
sludge from contaminated disposal areas. A preconditioning dewatering 
means for thickening and clarifying the sludge prior to comminuting the 
solids and filtrating to recover the phosphorus values are discussed. 
9. "Production of Phosphorus and Phosphoric Acid," James C. Barber, U.S. 
Pat. No. 4,608,241, Aug. 26, 1986. 
A multistep process for treating phosphorus-containing waste, for example, 
from H.sub.3 PO.sub.4 plants, is described. The steps include: (1) 
distilling the waste to separate phosphorus and water, which are condensed 
and separated into condensable and non-condensable gases; (2) 
agglomerating the residue with a binder and smelting the agglomerate in a 
submerged-arc furnace; (3) combining and burning the phosphorus from steps 
1 and 2 to give P.sub.2 O.sub.5 ; and (4) treating the P.sub.2 O.sub.5 
with water to give aqueous H.sub.3 PO.sub.4. Processes are also discussed 
for separating elemental phosphorus from the waste, converting the residue 
to granular fertilizer, and making suspension fertilizer from the water 
containing the phosphorus. Apparatus for the process is described in 
detail with diagram and flow charts. 
10. "Phosphorus Recovery from Phosphorus-Containing Pond Sludge," Steven M. 
Beck and Edward H. Cook, Jr., U.S. Pat. No. 4,717,558, Jan. 5, 1988. 
The title process, for phosphorus recovery from sludge containing 5-70% 
phosphorus, consists of mixing the sludge with additional water and 
heating with mild agitation at 165.degree.-212.degree. F. for 30 minutes 
or more to increase the phosphorus concentration in the sludge without 
compositional layering. The concentrated sludge settles, and is washed 
with water at 130.degree.-150.degree. F., the steps are repeated, and the 
sludge is recovered. Sludge 595 grams, containing phosphorus 21.9%, dirt 
19.2%, and water 48.9% was treated with additional water 1200 grams and 
heated at 169.degree. F. with mild agitation for about 90 minutes, after 
which the sludge was allowed to settle and give a bottom layer containing 
phosphorus 84.4, dirt 3.3, and water 12.3%. The sludge was sparged with 
hot (135.degree. F.) water at 2 liters per hour with continuous overflow 
to give, after 2 hours, 160 grams of material of composition phosphorus 
79.4%, dirt 1.8%, and water 18.8%, for example, about 97.5% phosphorus 
recovery. 
11. "Process for Treatment of Phossy Water for Recycling," Gordon H. 
Scherbel, David A. Crea, Jerry A. Keely, Ronald L. Andersen, and Byron L. 
Nichols, U.S. Pat. No. 4,744,971, May 17, 1988. 
In the electric furnace production of elemental phosphorus, cold phossy 
water (water contaminated with dirt and phosphorus) used for cooling and 
washing is segregated from hot phossy water used in condensing and 
handling liquid phosphorus. The cold phossy water is clarified, especially 
in a lined pond, and then recycled to the process. The hot phossy water is 
flocculated and clarified in a lamellar settler, and then recycled. 
Phosphorus in the sludge underflow from the settler is separated from the 
solids and recovered. Phosphorus at 145 pounds per day was recovered from 
a settler underflow in the clarification of hot phossy water containing 
306 ppm of phosphorus received at a rate of 40 gallons per minute. 
12. "Phosphorus Recovery from Phosphorus Mud," Michael A Nield and Basil N. 
Robbins, Canadian patent 1,267,267, Apr. 3, 1990. 
The title process comprises (a) completely boiling off the water from the 
waste material, (b) boiling off yellow phosphorus from the waste material, 
and (c) boiling off residual phosphorus from the treated waste material. 
An inert gas, for example, nitrogen, is blown through the waste material 
during stages a and b, and an oxygen-containing gas, for example air, is 
used in stage c to burn off the residual phosphorus. This method decreases 
the time required to process phosphorus mud to a safety disposable form. 
13. "Passivation of elementaI phosphorus contained in waste ponds," Auston 
K. Roberts, William E. Trainer, Mark L. Blumenfield, David L. Biederman, 
U.S. Pat. No. 4,961,912, Oct. 9, 1990. 
Elemental phosphorus-containing wastes in waste ponds are mixed with 
oxygen, or with an oxygen-nitrogen mixture, or air, and passivated to a 
substantially less pyrophoric material, which can be recovered as an 
aqueous phosphate solution. 
14. "Oxidation of Elemental Phosphorus in Water Under the Effect of 
Ionizing Radiation," N. P. Tarasova and Yu V. Balitskii, Zh. Prikl. Khim. 
(Leningrad), 64(6), 1172-7.The feasibility is shown of reagent-free 
oxidation of elemental phosphorus in wastewater by exposure to ionizing 
radiation (60 C. was used in the study). The process has a radical 
mechanism and proceeds through a number of intermediate stages. 
15. "Treatment of Wastewaters Containing Phosphorus, A. F. Gafarova, O. I. 
Grebenikov, G. V. Nad'Yarnykh, N. P. Tavasova and V. N. Chfstyakov, 
Russian patent 1,650,612, May 23, 1991. 
The process includes bubbling an oxygen-containing gaseous mixture at 
elevated temperatures in the raw slurry. White phosphorus is extracted and 
the purification degree of the phosphorus-containing wastewaters is 
increased when the bubbling is performed simultaneously with .gamma. 
irradiation at a 0.5-1.7 kilogram range of absorbed dosage (A), followed 
by separating phosphorus after stratifying the slurry and irradiating the 
remaining aqueous phase at 
##EQU2## 
(C=concentration of white phosphorus in the system, miligrams per liter; 
t=temperature .degree. C.) for initial phosphorus concentration of 4-150 
miligrams per liter, and 
##EQU3## 
C for initial phosphorus concentration of equal to or less than 4 
miligrams per liter and 30.degree.-70.degree.. 
16. "Recovery and Removal of Elemental Phosphorus from Electric Furnace 
Sludge," I. J. Anazia, J. Jung, and J. Hanna, Miner. Metall. Process., 
9(2), 64-8, 1992. 
Two samples (samples A and B) of phosphorus-containing sludges from 
electrothermal manufacture of elemental phosphorus were tested using 
physical separation techniques (sizing, froth flotation, and dispersed air 
oxidation) to recover elemental phosphorus as a concentrate and to render 
the residual material nonhazardous. Sample A was probably a mixture of 
phosphorus sludge, fly ash, and bottom ash, and sample B may have been 
neutralized with lime after deposition in the pond. In direct flotation of 
elemental phosphorus from sample-A sludge, the selectivity was achieved 
with minimum quantities of kerosine as the elemental phosphorus collector, 
whereas with sample B, xylene was a better collector. Flotation and sizing 
produced concentrations containing 69-90% elemental phosphorus with 
recovery 60-87%. Newly developed dispersed air oxidation of fines and 
tailings was effective in the removal of additional 10-15% elemental 
phosphorus from the sludge. 
EXAMPLE I 
Molten slag from electric furnaces operated at NFERC was quenched with 
water to granulate the material. A technical paper titled "Handling and 
Utilization of Phosphorus Furnace Slag," J. C. Barber and M. M. Striplin, 
Jr., was presented at the Electric Furnace Conference of the American 
Institute of Mining, Metallurgical, and Petroleum Engineers, November 
1960, in Chicago, Ill. The technical paper was published in the conference 
proceedings. 
The paper "Handling and Utilization of Phosphorus Furnace Slag" includes 
diagrams of the equipment to quench molten slag and the paper gives data 
on the performance of the quenching operation. Information in the present 
example was derived from the paper. 
Data on performance of the quenching operation were obtained when the 
phosphate smelted was a mixture of ores mined in Tennessee and Florida. 
Fifty-eight percent of the ore was from Tennessee deposits and 42 percent 
was from Florida deposits. The Tennessee phosphate was agglomerated by 
nodulizing and Florida phosphate concentrate was added to nodulizing kilns 
as substrate. Uncalcined Florida, pebble phosphate was fed to the electric 
furnaces without agglomeration. About 8.4 tons of molten slag was made per 
ton of elemental phosphorus produced. Typical composition of the slag is 
given in table 1. 
TABLE 1 
______________________________________ 
Typical Composition of Phosphorus Furnace Slag 
Constituent Percentage, dry basis 
______________________________________ 
CaO 46.0 
SiO.sub.2 38.0 
Al.sub.2 O.sub.3 
9.2 
P.sub.2 O.sub.5 
1.2 
F 2.8 
K.sub.2 O 1.2 
Na.sub.2 O 0.3 
Fe.sub.2 O.sub.3 
0.3 
MgO 0.3 
S 0.2 
MnO 0.2 
TiO.sub.2 0.1 
______________________________________ 
In addition to the constituents shown, the slag was analyzed for zinc, 
copper, boron, molybdenum, lead, tin, and lithium. The percentage of each 
of these materials was less than 0.1. Most of the constituents in the slag 
was derived from the phosphate fed to the furnace; therefore, tbe 
composition of the slag will vary with the source of phosphate. 
Normally, the slag was rapidly cooled by quenching with air or water and an 
amorphous, glassy material was formed. With slow cooling, calcium 
silicates crystallize. The specific density of the air-cooled slag was 180 
pounds per cubic foot. The bulk density varied widely, depending on the 
method of cooling and the particle size. 
Temperature of the molten slag was in the range of 2600.degree. to 
2700.degree. F. 
In order to make a slag tap, water was turned on the quenching and 
transporting nozzles and then the taphole was opened. A tapered steel plug 
was removed from the taphole and a hole was punched through the frozen 
slag with a steel bar. Sometimes it was necessary to melt out the frozen 
slag with an iron pipe ignited with oxygen, but this procedure was used 
only when necessary because of the high cost and the possibility of 
damaging the water-cooled tapping assembly. The taphole was closed by 
reinserting the steel plug. 
EXAMPLE II 
Example I describes conditions under which molten slag was quenched at 
NFERC. Example II gives performance data on the operation of the slag 
quenching facility, The data are given below. 
TABLE 2 
______________________________________ 
Operating Data for Quenching Molten Slag 
______________________________________ 
Slag temperature, degrees F. 
At taphole 2660 
Entering sluiceway 2470 
Tapping rates, ton per minute 
Average 0.4 
Maximum 1.0 
Pressure of water at nozzles, psi 
125 
Water required, gallons per ton 
2900 
slag quenched 
Slag size, percentage through 
10 mesh 93 
20 mesh 69 
48 mesh 13 
Cost of slag tapping and water 
quenching, dollars per ton.sup.a 
Tapping 1.07 
Water quenching 0.07 
Transportation to storage pile 
0.47 
Total 1.61 
______________________________________ 
.sup.a Costs in November 1960 which was date paper "Handling and 
Utilization of Phosphorus Furnace Slag" was presented. 
EXAMPLE III 
It was stated above in "Summary and Objects of the Invention" that one of 
the two primary objects was: 
To provide a process for the disposal of phossy water when the phossy water 
contains little or no settleable particles of elemental phosphorus. 
FIG. 3 is a photograph of phossy water in a settling pond at NFERC. The 
volume of phossy water in the settling pond was estimated to be 1,150,000 
cubic feet. The specific objective of the invention is to dispose of the 
large volume of phossy water shown in FIG. 3. 
The present example will show how phossy water can be disposed of by 
utilizing waste heat in molten slag. 
Data in table 2 show that the quantity of water required to quench and 
granulate molten-slag was 2900 gallons per ton. However, some of the water 
was consumed when the granulated slag was slurried in order to pump it to 
a storage pile. Water used to slurry the slag was discharged as a waste. 
Granulated slag can be hauled to storage and discharge of a liquid waste 
can be avoided. Water needed to quench and granulate slag will be less 
than 2900 gallons per ton if no water is needed for slurrying. 
The quantity of phossy water that will be evaporated from quenching slag 
made in a 50-megawatt furnace was calculated from the following 
conditions. 
1. Electric energy required to produce one ton of elemental phosphorus was 
taken to be 12,500 kWh. 
2. Operating time 90 percent of actual time. 
3. Specific heat of slag 0.3 
4. Slag made was 8.4 tons per ton of elemental phosphorus produced. 
5. Temperature of slag at sluiceway 1470.degree. F. 
6. Assume slag is cooled to 100.degree. F. by quenching. 
7. Net enthalpy of steam at 100.degree. F. is 1122 Btu per pound. 
##EQU4## 
A 25-megawatt furnace would be expected to have an average operating time 
of 95 percent. Calculations similar to those made above show that 148 days 
would be required to evaporate phossy water shown in FIG. 3. From these 
calculations it was concluded that a 25-megawatt furnace, or larger, is 
needed to evaporate water shown in FIG. 3 in a reasonable time. 
EXAMPLE IV 
Elemental phosphorus commonly used in industry is .varies. white 
phosphorus. However, the color is observed to be yellow. The .varies. 
white phosphorus usually contains small percentages of yellow phosphorus 
oxides. The .varies. white phosphorus is obtained by the condensation of 
phosphorus vapor, and the elemental phosphorus in phosphorus sludge and 
precipitator dust is .varies. white phosphorus. 
A common method of separating elemental phosphorus from its impurities is 
to heat impure phosphorus, such as phosphorus sludge, in a still. Water 
and elemental phosphorus vaporize and they are condensed thus obtaining 
phossy water and liquid phosphorus. 
The .varies. white phosphorus has a melting temperature of 112.degree. F. 
and a boiling temperature of 536.degree. F. When phosphorus sludge is 
heated to a temperature high enough to obtain rapid volatilization of 
elemental phosphorus, part of the phosphorus is converted into an 
amorphous form called red phosphorus. 
Red phosphorus has a low vapor pressure at the boiling temperature for 
.varies. white phosphorus, but it must be heated to about 750.degree. F. 
before it has a vapor pressure as high as one atmosphere. But it is 
impractical to vaporize red phosphorus in a still because the steel 
deteriorates by reaction between phosphorus and iron at the higher 
temperatures. Red phosphorus remains in the still residue. 
Red phosphorus does not burn when it is exposed to air. Particles 
comprising the still residue, including red phosphorus, can be aggregated 
into lumps suitable for smelting in an electric furnace. Since 
temperatures inside the electric furnace are as high as the range of 
2600.degree.-2700.degree. F., red phosphorus is readily vaporized, 
condensed, and recovered as .varies. white phosphorus when still residue 
is smelted. 
EXAMPLE V 
The disposal of phossy water by evaporation from contact with molten slag 
is applicable primarily for water containing dissolved elemental 
phosphorus and colloidal phosphorus particles. When phossy water contains 
settleable phosphorus particles, the concentration may be high enough to 
cause fuming. It was observed that slight fuming occurred on the surface 
of water in the settling pond, when the elemental phosphorus content of 
the water was in the range of 2 to 3 parts elemental phosphorus per mill, 
ion parts of water. And fuming occurred over the surface of phossy water 
in a clarifier used to treat phossy water generated during the 
condensation of elemental phosphorus. The elemental phosphorus content of 
the clarified phossy water was 120 parts per million parts of water. 
A mixture of phosphorus sludge and phossy water was stored in a tank at 
NFERC for 10 years. The phossy water was bleedoff from the phosphorus 
condensing system and it contained elemental phosphorus in the following 
forms. 
Dissolved elemental phosphorus 
Colloidal elemental phosphorus particles 
Settleable elemental phosphorus particles 
It is assumed that the original elemental phosphorus content of the phossy 
water was 1700 parts elemental phosphorus per million parts of water. 
After quiescent storage for 10 years, all the settleable particles of 
elemental phosphorus were settled into the lower layer of phosphorus 
sludge leaving only dissolved elemental phosphorus and colloidal elemental 
phosphorus particles. After 10 years settling the phossy water contained 
one part elemental phosphorus per million parts of water. 
The phossy water was recovered by using it to produce 13-38-0 grade of 
liquid suspension fertilizer. Phossy water was used instead of process 
water to make the fertilizer. There was no fuming from the surface of the 
phossy water. 
Based on somewhat fragmentary data, the upper limit of elemental phosphorus 
content for phossy water disposal by evaporation to dryness is taken to be 
two parts elemental phosphorus per million parts of water. With this 
concentration as a maximum, phossy water will not be loaded with 
settleable phosphorus particles. 
EXAMPLE VI 
Following is a statement in the book, "Handbook of Toxic and Hazardous 
Chemicals," Marshall Sittig, Noyes Publications, 1981, under "Phosphorus." 
Permissible Concentration in Water: The EPA (A-3) has proposed a criterion 
of 0.10 .mu.g/l yellow (elemental) phosphorus for marine or estuarine 
waters. Further EPA (A-37) has suggested a permissible ambient goal of 1.4 
.mu.g/liter based on health effects. 
The statement in "Handbook of Toxic and Hazardous Chemicals" provides a 
basis for a lower concentration of elemental phosphorus in phossy water. 
Phossy water containing less than 0.1 part elemental phosphorus per 
billion parts of water is outside the proposed criterion and does not 
require disposal as a hazardous material. 
EXAMPLE VII 
At some smelting furnaces molten slag is tapped and it flows into 
reservoirs. Molten slag is retained in the reservoirs by dikes made from 
tapping mud. The slag is cooled by applying process water on the surface 
of the pools of slag. The water evaporates from heat in the hot slag. 
Slag cracks when it solidifies from cooling by the application of waiter, 
The pieces of slag are crushed to prepare pieces small enough to be used 
as ballast. Cooling the slag by the application of water on the surface is 
an important part of the operation because slag must be solidified, 
transported to the crushing area, and new retention dikes made with 
tapping mud between furnace taps. 
Phossy water containing concentrations of elemental phosphorus in the range 
of 0.1 part elemental phosphorus per billion parts water to 2 parts per 
million can be used as the cooling medium instead of process water. 
EXAMPLE VIII 
A description of the operation of phosphorus condensers at NFERC is given 
in Chemical Engineering Report No. 3, titled "Production of Elemental 
Phosphorus by the Electric-Furnace Method," 1952. An abridged version is 
given in the present example, as follows. 
During normal operation the gas entered the precipitator at a temperature 
of 500.degree. to 700.degree. F., and then flowed to the spray condenser 
where it was cooled to a temperature of 130.degree. to 150.degree. F. by 
contact with phossy water. When phosphorus was pumped from the condenser 
sump, an equal volume of water was usually added to the sump. Phossy water 
then overflowed from the condensing system at rates ranging from 6 to 9 
gallons per hour as more phosphorus condensed and accumulated in the 
condenser sump. In order to permit the settling of suspended phosphorus 
particles in the discharged phossy water, a settling tank and basin were 
provided which collected the overflowing phossy water. The 15,000-gallon 
settling tank was built originally for storage of phosphorus. A concrete 
basin with an area of 1,150-square feet and, a volume of 24,000 gallons 
was provided under the settling tank. The excess phossy water entered the 
tank at one end and discharged at the opposite end. The phossy water then 
flowed through the basin under the tank to provide further settling of 
suspended phosphorus particles, Approximately 40 percent of the total 
elemental phosphorus was recovered in the settling tank and basin. 
After settling, the phossy water was used in phosphoric acid units for the 
hydration of P.sub.2 O.sub.5 to form acid and it was discharged into the 
settling pond shown in FIG. 1. After further settling in the pond, phossy 
water was discharged into a receiving stream called Pond Creek. 
Soda ash solution was added to the recirculating phossy water at the 
condenser to control the pH at a value of approximately 5.5. It was found 
in the laboratory that the titration of phossy water to a pH of 5.5 
required a relatively small quantity of sodium carbonate, but a 
considerably greater quantity was required to titrate to higher pH values. 
For example, titration of the phossy water from a pH of 2 to a pH of 6 
required about twice the quantity of sodium carbonate that was required to 
titrate the phossy water from a pH of 2 to a pH of 5.5. 
EXAMPLE IX 
When the phosphorus condensers were operated as described in example VIII 
phosphate ore was mined in Tennessee, the ore was beneficiated by washing 
out the clay, and the ore was agglomerated by nodulizing. The ore had to 
be heated to relatively high temperatures to nodulize the material and 
much fluorine was volatilized. In the case of example VIII the 
beneficiated ore had a F:P.sub.2 O.sub.5 weight ratio 0.105 and the 
nodulized ore had a ratio of 0.080, indicating about 23 percent of the 
fluorine was volatilized. 
It was reported in example VIII that 6 to 9 gallons per hour of phossy 
water was bled from the condensing system at one of the furnaces. 
Tennessee phosphate ore which was amenable to beneficiation by washing 
became exhausted. The phosphate could be agglomerated at a lower 
temperature than the beneficiated phosphate because it contained clay. 
Only about 8 percent of the fluorine was volatilized during agglomeration 
as discussed in a publication entitled "Fluoride Recovery from Phosphorus 
Production," J. C. Barber and T. D. Farr, Chemical Engineering Progress, 
volume 66, No. 11. Furthermore, the unbeneficiated feedstock had to be 
upgraded and some uncalcined Florida pebble was used as feedstock. Florida 
phosphate concentrate was fed to the nodulizing kilns where it was 
incorporated in the agglomerates. 
The overall result was that the F:P.sub.2 O.sub.5 weight ratio in the 
phosphate fed to the electric furnaces was substantially greater than 
0.080. With high F:P.sub.2 O.sub.5 weight ratios the amount of fluorine 
volatilized from the phosphorus furnaces increases. The relationship 
between the F:P.sub.2 O.sub.5 weight ratio in the feed material and the 
quantity of fluorine volatilized from the furnace is discussed in greater 
detail in "Fluoride Recovery from Phosphorus Production." 
Fluorine volatilizes from the furnace as SiF.sub.4 and in the condensing 
system this compound combines with phossy water in accordance with the 
following equation. 
EQU 3SiF.sub.4 +2H.sub.2 0=2H.sub.2 SiF.sub.6 +SiO.sub.2. 
Soda ash solution was added to the recirculating phossy water at the 
condenser to control the pH at a value of approximately 5.5, as stated in 
example VIII. Fluosilicic acid was neutralized with soda ash to form the 
salt Na.sub.2 SiF.sub.6 which has a low solubility and precipitates as a 
scale on heat transfer surfaces, in pumps, and in, spray nozzles. The 
formation of scale, on the equipment was the source of serious operating 
problems and it was necessary to prevent the precipitation of fluosilicate 
salts. The following operating steps were taken. 
1. Phossy water used to condense elemental phosphorus was neutralized by 
adding alkaline ammonium compounds instead of soda ash. The ammonium 
compounds reacted with fluosilicic acid in the phossy water to form 
ammonium fluosilicate which has greater solubility in water than does 
sodium fluosilicate. Nevertheless, sodium and potassium fluosilicates 
continued to precipitate in phossy water because sodium and potassium 
compounds volatilize from the phosphorus furnace and sufficient sodium 
and. potassium collects in the phossy water to form scales. 
2. The concentration of fluorine in phossy water was controlled so that 
sodium and potassium fluosilicates did not precipitate. From experience it 
was determined that maximum concentration of about 10 grams F per liter of 
phossy water was sufficient to prevent scale deposits. Phossy water was 
bled from the phosphorus condensing system and replaced with process water 
to control the concentration of F. Bleedoff of phossy water at high rates 
increases the water pollution problem. 
3. Sedimentation equipment was installed to treat the phossy water. The 
equipment is described in the publication "Waste Effluent; Treatment and 
Reuse," J. C. Barber, Chemical Engineering Progress, volume 65, No. 6. The 
water pollution problem was ameliorated by clarifying the phossy water and 
returning part of it to the phosphorus condensing system. 
EXAMPLE X 
Exhaust gases from production of wet-process phosphoric acid contain 
fluorine as SiF.sub.4 and HF. The exhaust gases are scrubbed with water 
from gypsum ponds, but this water contains small concentrations of sodium 
and potassium compounds. When scrubbers are used to absorb fluorine 
compounds from the exhaust gases, fluosilicate scale is deposited on the 
tower packing and the absorption efficiency is impaired. 
Although fluosilicate salts have greater solubility in acidic gypsum pond 
water than in neutral or alkaline solutions, producers of wet-process 
phosphoric acid have resorted to the use of spray towers to avoid scaling 
of tower packing. However, fluorine compounds are acidic and absorption 
efficiency is lower than it would be with a neutral or alkaline scrubbing 
medium. 
U.S. Pat. No. 4,613,494 discloses a process for absorption of the fluorine 
compounds in an ammoniacal solution having a pH in the range of 5.5 to 
6.0. The solution is slightly acidic and little ammonia would be lost, but 
the absorption efficiency would be greater than with low-pH pond water. 
Fluosilicic acid in the scrubbing medium is converted to fluoride salts by 
adding ammonia to a bleedoff stream to increase the pH to the range of 8.5 
to 9.0 as shown by the following equation. 
EQU H.sub.2 SiF.sub.6 +6NH.sub.3 +2H.sub.2 O=6NH.sub.4 F+SiO.sub.2. 
The high-pH solution can be added to the scrubbing medium to maintain the 
pH of the scrubbing medium in the range of 5.5 to 6.0. 
EXAMPLE XI 
U.S. Pat. No. 4,968,499 discloses a process for the conversion of a 
hazardous waste stored at NFERC into phosphorus furnace feedstock. The 
waste is precipitator dust and it is estimated approximately 20,000 tons 
has accumulated at NFERC. Composition of precipitator dust is given in 
table 3. 
TABLE 3 
______________________________________ 
Composition of Precipitator Dust 
Percent, 
dry basis 
______________________________________ 
P.sub.2 O.sub.5 27.7 
Elemental phosphorus 
0.3 
CaO 13.8 
SiO.sub.2 17.3 
Fe.sub.2 O.sub.3 1.7 
Al.sub.2 O.sub.3 3.6 
F 6.3 
K.sub.2 O 17.4 
MgO 0.9 
MnO.sub.2 0.1 
Na.sub.2 O 3.1 
S 0.1 
Total 92.3 
______________________________________ 
It is proposed to agglomerate the precipitator dust by tumbling it with a 
binder formed by reacting phosphoric acid with finely divided phosphate 
ore. The proportions of phosphoric acid and finely divided phosphate ore 
will be adjusted so that the reacted product will have a P.sub.2 O.sub.5 
:CaO mole ratio of about 0.92 which is the mole ratio in concentrated 
superphosphate. 
EXAMPLE XII 
Agglomerates prepared in accordance with example XI will be dried by 
heating in the temperature range of 300.degree. to about 800.degree. F., 
as called for in U.S. Pat. No. 4,968,499. 
Much technology is available on the preparation of concentrated 
superphosphate in the publication, "Development of Processes for 
Production of Concentrated Superphosphate," G. L. Bridger, Tennessee 
Valley Authority, Chemical Engineering Report No. 5, 1949. Binder for 
agglomeration of precipitator dust will be prepared in accordance with 
technology reported in "Development of Processes for Production of 
Concentrated Superphosphate." The normal composition of the agglomerates 
will be about two-thirds precipitator dust and one-third binder 
(concentrated superphosphate). Larger proportions of binder may be used if 
needed to increase the grade (% P.sub.2 O.sub.5) in the agglomerates. 
The dried agglomerates can be smelted to produce about 5,292 tons of 
elemental phosphorus, thus providing a process to recycle 34,000 tons of 
precipitator dust (wet basis). At the current market price of $0.91 per 
pound, the value of the elemental phosphorus will be nearly $10 million. 
From composition of precipitator dust in table 3 it is evident the 
F:P.sub.2 O.sub.5 weight ratio is 0.227. Precipitator dust will be 
agglomerated with monocalcium phosphate binder prepared by a process 
identical to that used to make concentrated superphosphate. The F:P.sub.2 
O.sub.5 weight ratio of green concentrated superphosphate is about 0.032. 
Since feedstock will normally be comprised of about one-third binder and 
two-thirds precipitator dust, the F:P.sub.2 O.sub.5 weight ratio of the 
feedstock will be about 0.162. 
In example VIII it was reported that phossy water was bled from the 
condensing system at a rate of 6 to 9 gallons per hour when the F:P.sub.2 
O.sub.5 weight ratio of the feedstock was 0.080. And in example IX it was 
reported that precipitation of fluosilicate salts as scales caused 
condensing system operating problems when the F:P.sub.2 O.sub.5 weight 
ratio was greater than 0.080. 
At a F:P.sub.2 O.sub.5 weight ratio 0.162, serious condensing system 
operating problems are expected when feedstock prepared from precipitator 
dust is smelted, The process to recycle precipitator dust was further 
developed to provide a method for coping with this problem. 
It is well known that fluosilicic acid and fluosilicate salts are converted 
to ammonium fluoride by ammoniation to a pH in the range of 8.5 to 9.0. 
Ammonium fluoride is highly soluble in water and the fluosilicate scale 
problem can be corrected by this conversion, Silica is precipitated when 
fluosilicates are converted to ammonium fluoride. 
The further development of the process to recycle precipitator dust is 
illustrated in FIG. 5. Phossy water can be bled from the condensing system 
and ammoniated to convert the fluosilicate salts to soluble fluorides. A 
slurry containing precipitated silica is formed. Phossy water from the 
process to convert precipitator dust into phosphorus furnace feedstock is 
added to the slurry and the mixture is clarified. Overflow from the 
clarifier is returned to the condensing system, but a stream of clarified 
phossy water is bled off to prevent an excessive concentration of 
dissolved ammonium phosphate since large concentrations of the salt may 
affect the physical characteristics of the phossy water. 
Underflow from the clarifier will be distilled and a residue will be 
obtained which contains silica, combined phosphorus, and red phosphorus. 
The residue can be agglomerated, dried, and smelted to recover the 
phosphorus values and silica. 
Water is lost from the condensing system as phossy water added to fluid 
fertilizers, as water vapor from the distillation of residue, and as water 
vapor in noncondensable gas. In accordance with the process illustrated in 
FIG. 6, phossy water obtained during the conversion of precipitator dust 
into furnace feedstock will be makeup water for the condensing system. 
EXAMPLE XIII 
FIG. 1 is a settling pond which was partially filled with phosphorus 
sludge. U.S. Pat. No. 4,608,241 discloses a process for treating the 
phosphorus sludge by distilling it to vaporize phosphorus and water and 
thereby separate the volatile materials from the nonvolatile residue. The 
residue will be agglomerated and smelted to produce elemental phosphorus 
in order to recycle the hazardous waste. 
As in example XI agglomerated residue will contain .varies. white 
phosphorus, or red phosphorus, or both, depending on the still 
temperature. 
Chemical composition of elemental phosphorus-free phosphorus sludge was 
reported in U.S. Pat. No. 3,084,029 and this analysis is given in table 4. 
TABLE 4 
______________________________________ 
Analysis of Phosphorus Sludge.sup.a 
Percent, 
dry basis 
______________________________________ 
P.sub.2 O.sub.5 
32 
CaO 8 
SiO.sub.2 
7 
F 23 
______________________________________ 
.sup.a Analysis is on an elemental phosphorusfree basis. 
The still residue has a F:P.sub.2 O.sub.5 weight ratio of 0.719 but after 
combining it with monocalcium phosphate the ratio will he reduced to 
0.491. In this case the F:P.sub.2 O.sub.5 weight ratio is 6.1 times the 
ratio of 0.080 in example VIII. In example VIII the phosphorus condensing 
system could be operated at a relatively low phossy water bleedoff rate of 
6 to 9 gallons per hour. Much fluorine will be volatilized when the 
phosphorus sludge is distilled, residue is agglomerated, and agglomerates 
are dried. However, the volatilized fluorine will be collected in the 
phossy water, and the phossy water will be used as makeup water for the 
phosphorus condensing system as described in example XII. A F:P.sub.2 
O.sub.5 weight ratio of 0.491 in the green agglomerates is tantamount to 
smelting feedstock having this F:P.sub.2 O.sub.5 ratio. 
EXAMPLE XIV 
One of the objectives of the present invention is to provide a process for 
the recovery of phossy water when the phossy water contains dissolved 
elemental phosphorous, colloidal particles of elemental phosphorus, and 
settleable particles of elemental phosphorus. When phossy water is 
generated in phosphorus condensing systems, water comes in intimate 
contact with gas containing elemental phosphorus vapor. Some of the 
elemental phosphorus condenses as colloidal particles and as settleable 
particles. 
A publication, "Waste Effluent; Treatment and Reuse," J. C. Barber, 
Chemical Engineering Progress, volume 65, No. 6, describes a process for 
clarifying phossy water generated in phosphorus condensing systems by 
sedimentation means. Clarified phossy water was returned to the condensing 
system. Phossy water containing 1700 ppm of elemental phosphorus was bled 
from the condensing system and clarified. The clarified overflow 
contained. 120 ppm of elemental phosphorus. Although the clarifier removed 
a, bout 93 percent of the elemental phosphorus, at an elemental phosphorus 
concentration of 120 ppm it is obvious that the elemental phosphorus 
content of clarified phossy water was mainly settleable particles. After 
settling for 10 years the elemental phosphorus content was reduced to 
about 1 ppm. 
A large (but unknown) quantity of phosphorus sludge has accumulated in the 
settling pond shown in FIG. 1. It is planned to recover the phosphorus 
sludge by distillation wherein elemental phosphorus will be vaporized and 
then condensed by contacting the phosphorus vapor with water as in the 
phosphorus condensing system. The elemental phosphorus content of the 
phossy water is expected to be about 1700 ppm, but clarification is 
expected to reduce the elemental phosphorus content to about 120 ppm. 
About 20,000 tons of precipitator dust is stored at NFERC and it is planned 
to recover this waste by agglomerating the precipitator dust and then 
heating the agglomerates to harden them. Elemental phosphorus will be 
vaporized and the vapor will be condensed by contacting the vaporized 
gases with water. Phossy water containing about 1700 ppm of elemental 
phosphorus will be generated. 
It is planned to conduct an engineering study at an existing submerged-arc 
electric furnace to investigate the smelting of feedstock prepared from 
precipitator dust. Part of the engineering study will include cooling the 
furnace gas by contacting the furnace gas with phossy water containing 
ammonia. Phossy water generated by contacting phosphorus vapor with water 
will be ammoniated to a pH in the range of 8.5 to 9.0 to convert 
fluosilicate to ammonium fluoride and the resulting slurry will be 
clarified by a sedimentation method or by centrifugation, or both. 
Data from the engineering study will provide a basis for the design of a 
phossy water recovery system. For example, mixing phossy water with slurry 
from the ammoniator, as shown in FIG. 5, may not be the preferred 
arrangement. The preferred arrangement may be addition of phossy water to 
the ammoniator. 
A larger than normal makeup water rate may be needed. An evaporator may be 
provided to concentrate clarified phossy water. Increase of water vapor 
loss by evaporation will provide larger additions of phossy water as 
makeup. 
The diagram shown in FIG. 5 may not be the optimum for recovery of phossy 
water. However, the diagram provides a guide for conducting the 
engineering study. Final arrangement of the equipment will depend on 
results of the engineering study.