Patent GB-828883-A (GB)
Title: Production of fertilizers
Inventor: ARNOLD JOHN CONRAD
IPC: C05B1/02
Filed: 1955-11-28
Abstract: In a process for the manufacture of a fertilizer product which involves the digestion of fertilizer raw material with mineral acid, the digestion is effected in the absence of extraneously applied heat with a preponderantly dry acidic sludge containing the mineral acid together with a fertilizer ingredient, the fertilizer ingredient and the fertilizer raw material being such as to result in a compound fertilizer.  The mineral acid may be sulphuric or phosphoric acid, and the fertilizer raw material may be any material, such as phosphate rock or dolomitic limestone, alone or together, which as the result of treatment with the mineral acid is rendered useful or more useful as a plant nutrient.  The sludge may be prepared by mixing the fertilizer ingredient with the acid, either all the acid being added at once or, where there is a chemical reaction between the acid and the fertilizer ingredient, as with ammonia or potassium chloride and sulphuric acid, additional acid may be added at a later stage to ensure the desired acid reaction.  The fertilizer ingredient may contain one or more of the elements nitrogen, phosphorus, potassium, calcium, or sulphur.  The sludge may have three parts by weight of dry material to one of wet material.  During the mixing of the sludge or subsequent dry-mixing of the sludge and the raw material, additional fertilizer ingredients containing nitrogen, potassium, or metal salts useful for plant growth may be added.  When processing phosphate rock, the procedure of Specification 828,881 may be employed.  The reaction product of the acidic sludge and phosphate rock may be pelleted as described in Specification 828,882. Sulphuric acid may be used to absorb ammonia obtained in the destructive distillation of coal until approximately 75% of the acidic ammonium sulphate is in solid form, the sulphuric acid being of higher concentration than normal.  The product is used as the acidic sludge.  Phosphoric acid may be used in place of the sulphuric acid.  In Example 1, a sludge prepared by absorbing 269 pounds of ammonia in 1423 pounds of sulphuric acid of 60 DEG  B. and at 60 DEG F. is mixed with 530 pounds of phosphate rock.  After the completion of the primary chemical reaction, the mixture is formed into agglomerations and coated with 120 pounds of additional rock to form pellets, which may be cured in the manner of Specification 828,881. Where fine superphosphate is required, 650 pounds of rock are used in the original mixture.  In Example 2, a mixture of ground phosphate rock and potassium chloride is added to sludge as in Example 1, and then treated similarly to form pellets.  In Example 3, 880 pounds of potassium chloride are mixed with 1512 pounds of sulphuric acid for 5 minutes and after about 300 pounds of HCl have been evolved and removed, 1325 pounds of phosphate rock are added.  The mixture is treated similarly to Example 1 to form pellets.  Alternatively, the sludge may be mixed with 1440 pounds of phosphate rock and cured in a ventilated pile.  The sludge may also be formed by mixing pure or crude potassium sulphate with the acid.  In Example 4, potassium chloride is mixed with sulphuric acid from 3 to 5 minutes, and ground dolomite added.  The coarse particles of dolomite may be added first and the finer particles later.  Example 5 is similar.  In Example 6, ammonium sulphate sludge is mixed with dolomite and phosphate rock. In Example 7, potassium chloride is mixed with sulphuric acid, and HCl driven off, phosphate rock and dolomite are mixed in, and then dry ammonium sulphate is added.  The mass is poured into a den, disintegrated, pelleted, and coated with ground dolomite.  A sludge obtained by mixing ground phosphate rock with sulphuric acid and removing dilute phosphoric acid may be used alone or with other sludges.  In Example 8, ammonium sulphate, potassium chloride, and a gypsum sludge containing 3.2% P2O5 is mixed, pelleted, and coated with ground phosphate rock.  In Example 9, gypsum sludge as in Example 8, potassium chloride, ammonium sulphate sludge, and ground phosphate rock are mixed, pelleted, and coated with additional phosphate rock.  Commercial gypsum or a nonacid gypsum sludge may be mixed with an acidic sludge.ALSO:In a process for the manufacture of a fertilizer product which involves the digestion of fertilizer raw material with mineral acid, the digestion is effected in the absence of extraneously applied heat with a preponderantly dry acidic sludge containing the mineral acid together with a fertilizer ingredient, the fertilizer ingredient and the fertilizer raw material being such as to result in a compound fertilizer.  The mineral acid may be sulphuric or phosphoric acid, and the fertilizer raw material may be any material, such as phosphate rock or dolomitic limestone, alone or together, which as the result of treatment with the mineral acid is rendered useful or more useful as a plant nutrient.  The sludge may be prepared by mixing the fertilizer ingredient with the acid, either all the acid being added at once or, where there is a chemical reaction between the acid and the fertilizer ingredient, as with ammonia or potassium chloride and sulphuric acid, additional acid may be added at a later stage to ensure the desired acid reaction.  The fertilizer ingredient may contain one or more of the elements nitrogen, phosphorus, potassium, calcium, or sulphur.  The sludge may have three parts by weight of dry material to one of wet material. During the mixing of the sludge or subsequent dry-mixing of the sludge and the raw material, additional fertilizer ingredients containing nitrogen, potassium, or metal salts useful for plant growth may be added.  When processing phosphate rock, the procedure of Specification 828,881, may be employed.  The reaction product of the acidic sludge and phosphate rock may be pelleted as described in Specification 828,882.  Sulphuric acid may be used to absorb ammonia obtained in the destructive distillation of coal until approximately 75% of the acidic ammonium sulphate is in solid form, the sulphuric acid being of higher concentration than normal.  The product is used as the acidic sludge.  Phosphoric acid may be used in place of the sulphuric acid.  In Example 1, a sludge prepared by absorbing 269 pounds of ammonia in 1423 pounds of sulphuric acid of 60 DEG B and 60 DEG F is mixed with 530 pounds of phosphate rock.  After the completion of the primary chemical reaction, the mixture is formed into agglomerations and coated with 120 pounds of additional rock to form pellets, which may be cured in the manner of Specification 828,881.  Where fine superphosphate is required, 650 pounds of rock are used in the original mixture.  In Example 2, a mixture of ground phosphate rock and potassium chloride is added to sludge as in Example 1, and then treated similarly to form pellets.  In Example 3, 880 pounds of potassium chloride are mixed with 1512 pounds of sulphuric acid for 5 minutes and after about 300 pounds of HC1 have been evolved and removed, 1325 pounds of phosphate rock are added. The mixture is treated similarly to Example 1 to form pellets. Alternatively, the sludge may be mixed with 1440 pounds of phosphate rock and cured in a ventilated pile.  The sludge may also be formed by mixing pure or crude potassium sulphate with the acid.  In Example 4, potassium chloride is mixed with sulphuric acid from 3 to 5 minutes, and ground dolomite added.  The coarse particles of dolomite may be added first and the finer particles later.  Example 5 is similar.  In Example 6, ammonium sulphate sludge is mixed with dolomite and phosphate rock.  In Example 7, potassium chloride is mixed with sulphuric acid and HC1 driven off, phosphate rock and dolomite are mixed in, and then dry ammonium sulphate is added.  The mass is poured into a den, disintegrated, pelleted, and coated with ground dolomite.  A sludge obtained by mixing ground phosphate rock with sulphuric acid and removing dilute phosphoric acid may be used alone or with other sludges.  In Example 8, ammonium sulphate, potassium chloride, and a gypsum sludge containing 3.2% P2O5 is mixed, pelleted, and coated with ground phosphate rock.  In Example 9, gypsum sludge as in Example 8, potassium chloride, ammonium sulphate sludge, and ground phosphate rock are mixed, pelleted, and coated with additional phosphate rock.  Commercial gypsum or a non-acid gypsum sludge may be mixed with an acidic sludge.