Patent Publication Number: US-3877929-A

Title: Process for reducing iron content of titaniferous material

Description:
Whitehead et al.  
 PROCESS FOR REDUCING IRON CONTENT OF TITANIFEROUS MATERIAL Related U.S. Application Data Continuation of Ser. No. 60,124, July 31, 1970.  
 Foreign Application Priority Data July 31, 1969 United Kingdom 38475/69 U.S. Cl 75/1; 75/26 Int. Cl. C22b 1/10; C22b 53/00 Field of Search 60/124, 127, 123; 75/1 T,  
 References Cited UNITED STATES PATENTS 8/1938 Dawson et a1. 423/86 Apr. 15, 1975 2,339,808 1/1944 Ravnestat et a1. 75/1 X 2,758,019 8/1956 Daubenspeck et a1.. 75/1 2,900,246 8/1959 Keith et a1. 75/35 X 3,383,200 5/1968 Valk 75/1 X 3,457,037 7/1969 Aramendia et a]. 75/101 X 3,473,916 10/1969 Severns, Jr 75/26 X 3,589,892 6/1971 Peterson 75/72 3,597,189 8/1971 Sinha et al. 75/1 Primary Examiner-Allen B. Curtis Attorney, Agent, or FirmSchuy1er, Birch, Swindler,  
 McKie &amp; Beckett [57] ABSTRACT A process for the beneficiation of ironcontaining titaniferous material in which, during one stage of the beneficiation, the iron content of the material is reduced with hydrogen in the presence of added steam to control the rate of reduction.  
 11 Claims, No Drawings PROCESS FOR REDUCING IRON CONTENT OF TITANIFEROUS MATERIAL This is a continuation of application Ser. No. 60124, filed July 31, 1970.  
  The present invention relates to the reduction of ironcontaining materials, particularly to the reduction of ironcontaining titaniferous materials.  
  In some processes for the beneficiation of ironcontaining titaniferous material such as ilmenite or leucoxene it is advisable to reduce the iron content substantially wholly to the ferrous state while avoiding the formation of significant amounts of metallic iron or trivalent titanium. For example, a suitable product from such a process is one which contains not more than 2 percent of the iron content in a form other than the ferrous state.  
  In the past the control of the reduction at elevated temperature to produce such a product has been found difficult.  
  For example, when hydrogen is used the reduction is generally so rapid that it is difficult to avoid the formation of unacceptable amounts of metallic iron and/or trivalent titanium. When a solid reductant such as carbon is used, on the other hand, it has been found that at temperatures up to about 1,000C the reduction is unacceptably slow whereas at higher temperatures it is very rapid and gives rise to excessive amounts of metallic iron.  
  One method by which the foregoing difficulties may be avoided is by the use of hydrocarbon containing from 1 to 4 carbon atoms, particularly methane, as a reductant.  
  It is an object of the present invention to provide another method whereby these difficulties may be overcome.  
  Accordingly, the present invention is a process for reducing the iron content of iron-containing titaniferous material by contacting the material at an elevated temperature with hydrogen in the presence of added steam.  
  The iron-containing titaniferous material is normally an ilmenite or leucoxene and preferably the former. Such materials may have an iron content in the range of about 5 to 55 percent and more commonly one in the range 30 to 46 percent by weight (expressed as FeO).  
  The iron-containing titaniferous material is preferably contacted with the reducing agent when in finelydivided form, for exaample when having an average particle, size in the range 50p. to 300p, and preferably one in the range 100p. to 200;!  
 as nitrogen, argon or carbon dioxide into the hydrogen/steam mixture, for example to ensure fluidisation and/or to assist in controlling the rate of reaction.  
 Temperatures at which the iron-containing titaniferous material may be contacted with hydrogen and steam (and other gas if present) are suitably in the range 600C to 1, C but are more preferably in the range 650C to 950C and particularly in the range 700C to 900C.  
  The process is conveniently carried out in a continuous manner, i.e. in which reduced material is continuously or intermittently removed froin, and unreduced material is continuously and intermittently added to, the reaction zone.  
  The proportion of steam added to the hydrogen will determine the degree of reduction which takes place. For example, when using hyrogen without the introduction of steam both metallic iron and trivalent titanium are normally formed as well as ferrous iron if the reduction period is prolonged. As the proportion of steam introduced is progressively increased, say up to 10 percent by volume on the hydrogen present, the amount of metallic iron formed falls (and generally becomes constant at a very low figure) while the amount of ferrous iron (as opposed to ferric iron) may also fall slightly. It is preferred, therefore, to add an amount of steam which gives a product with a very small proportion of metallic iron and a very high proportion of ferrous iron. Proportions of about 1 to 7 percent steam are therefore preferred, particularly proportions in the range 2 percent to 5 percent, by volume on the hydrogen present.  
  The process of the present invention is particularly suitable for reducing iron-containing titaniferous material which has been subjected to a preliminary oxidation step and/or which will subsequently be subjected to a leaching step, for example with a mineral acid such as aqueous hydrochloric acid to remove the reduced iron. In the latter case the comparative absence of trivalent titanium and ferric salts is of particular value if the solution is to be subsequently treated to recover finely-divided iron or iron oxide and/or to recover hydrogen chloride, for example, by the Aman process.  
  The following Example shows various embodiments of the process of the present invention.  
 EXAMPLE A beach sand ilmenite containing 39.5 percent by weight of iron (expressed as FeO) was oxidised at 875C until substantially all the iron was in the ferric state.  
  Equal quantities of the material were then placed in turn into a 3 inch diameter bed and the bed was heated. When the temperature reached 700C the bed was fluidised with hydrogen and with mixtures of hydrogen and steam at a flow rate five times the minimum fluidising velocity for the times shown in Table 1 while maintaining the temperature of 700C.  
  The materials were analysed after reduction for 60 minutes and the results are given in Table 2.  
 TABLE 1 7: FeO* after minutes Nomi H2 flow rate H2O flow I nal l/min. ml. of 7c v/v at ambient liquid per l0 H2O temperature minute Table 2 4. A process as claimed in claim 1 wherein the iron- Analysis of bulk sample after 60 minutes containing titaniferous material has an average particle metallic Fe Ti o FeO* 5126 m the range 4 to M- 15 5. A process as claimed in claim 4 wherein the averg 8:; Y2: 3. age particle size is in the range 100/.L to 200 1.. 5 0.2 0.4 38.0 6. A process as claimed in claim 1 wherein an inert 10 0 gas is added with the hydrogen and steam.  
  In the FeO determination, metallic irpn and part ofthe trivalent titanium will be 7. A process as claimed in claim 1 wherein the mate- Lise-$221; easfeo. This explains the hlgherlevels whenhydrogenonly is used as 20 rial is heated to a temperature in the range 700C to Note: 900  
 The apparent excess of iron (expressed as FeO) after reduction with hydrogen C over that of the starting material is due to the presence of metallic iron and some 8. A PI&#39;OCESS 8S clalmed in claim 1 wherein the retrivalenttitanium(whichareestimatedasFeObythemethodofanalysis). duced material is leached with a mineral acid to Wmt is Claimed is: move iron from the titaniferous material and solid benl. A process for reducing the iron content co i eficlated e ous material is separated from the titaniferous material comprising oxidising said titanifer penslon&#39; ous material until substantially all the iron content is in The Process of&#39;clalm wherem 1h addlhoh to 531d the ferric state, and contacting said oxidised material in added Steam there a lhcfhporatfad ah men gas a fluidised bed at a temperature within the range acted frcfm group conslshhg mtrogeh, argon and 650C. to 950C. with a mixture of hydrogen and added carbon dloxlde to flulchsahohsteam until not more than 2 percent of the iron content T Process of clafm 9 W h 531d htahlferous of said material is in a form other than the ferrous state, matenal contacted sald mlxtul&#39;e m a flhldlsed the proportion of steam in the mixture being in the the flow rate Pfgases h sald h belhg the range of about 2 to 5 percent by volume of hydrogen 35 range five to 15 times the mmimum fluidismg velocity 2. A process as claimed in claim 1 wherein the ironof sald l containing titaniferous material is ilmenite or leucox- T process of cla&#39;lm 1 W htahlfel&#39;ous ens material 15 contacted with said mixture in a fluidised 3. A process as claimed in claim 1 wherein the ironh the flow rate of h gases f hg said bed being containing titaniferous material has an iron content in 40 m h range five to 15 the mlmmhm fhhdlslhg the range 30 to 46 percent by weight as expressed as [Duty of the FeO.  
  UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 877, 929 Dated April 15, 1975 Inventor(s) Whitehead et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
  Under the heading &#34;Inventors&#34;, after Stockton-on-Tees, the phrase &#34;both of England&#34; should be deleted and the phrase Alan Conners, Delamere, Stockcroft Road, Balcombe, Sussex; and Derek Vernon Gosden, Reksley House, Shipley Road, Southwater, Horsham, Sussex, all of England should be inserted.  
  Between the headings &#34;Inventors&#34; and Filed&#34;, the heading and phrase Assignee: British Titan Limited, Billingham, Teesside, England should be inserted.  
 Signed and Scaled this thirteenth Day of April 1976 [SEAL] Arrest:  
 RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parents and Trademarks