Patent GB-438114-A (GB)
Title: Improved soil improvers and a process for their manufacture
IPC: C05F11/02
Filed: 1934-04-03
Abstract: Soil improvers are obtained by maintaining a mixture comprising materials containing humin acids and materials containing or yielding hydrated silicic acid and hydrated alumina in a moist condition at elevated temperature for a sufficient time to produce colloidal complex compounds of humin acids, silicic acid and alumina.  The hydrated silicic acid and/or hydrated alumina may be produced during the process by the hydrolysis of silicates, especially readily hydrolizable aluminosilicates of bivalent bases.  The humin acids may be added as lignite or ammoniacal extracts thereof or may be produced in situ by oxidation of recent or fossil organic materials or the oxidation may take place before the admixture of the other substances; suitable materials for oxidation are peat, straw, chaff, husks, wood pulp, &c.  Suitable aluminosilicates may be obtained by rapidly cooling molten mixtures containing the constituents.  The silicates may also contain monovalent bases such as potassium.  A commercial calcium aluminosilicate containing small amounts of iron and manganese sold under the name "Silicakalk" may be used.  During the oxidation, the pH should be below 9 and preferably in the range 6-7.  The pH may be controlled or periodically varied during the reaction by the introduction of ammonia.  The final pH of the product may be adjusted between 6 and 7 e.g. by the addition of ammonia or potassium hydroxide.  The formation of the colloidal complex compounds and/or the oxidation may be effected in the presence of iron and/or manganese compounds, e.g. ferrous or ferric sulphate, manganese oxide and manganese sulphate but especially reduced iron. After oxidation, the material may be saturated with ammonia the excess of ammonia being preferably subsequently removed say by a current of air.  Temperatures not exceeding 130 DEG  C., say below 100 DEG  C. are preferably employed in the process.  The process may be conducted in a gas-tight silo provided with a perforated plate near the bottom and a water-sealed cover, the reaction gases, e.g. air (oxygen or ozonized air), ammonia and water vapour being introduced from below.  According to examples: (1) a moist mixture of sphagnum peat, "Silicakalk," manganese dioxide and ferric oxide is treated with a current of air, water vapour and sufficient ammonia to control the pH at 5-7 for ten days, followed by treatment with excess of ammonia and subsequent treatment with a current of air to remove this excess and bring the pH of the product to 6-7; (2) humic substance precipitated from an ammoniacal extract of lignite is mixed with "Silicakalk" the mixture being maintained in a moist condition at 70 DEG  C. for 24 hours; (3) a moist mixture of sphagnum peat and reduced iron is treated at 70 DEG  C. with a stream of humid air containing sufficient ammonia to maintain a pH of 6-7, the product being mixed with "Silicakalk" and maintained at 70 DEG  C.; (4) the product of example (1) is again oxidized at pH 5-7 followed by treatment with ammonia, this sequence being repeated yet a third time followed by removal of the ammonia by air.  Specifications 347,641 and 419,387 are referred to.