FI73659C - Preparation process for combined phosphorus fertilizers and soil enhancers. - Google Patents

Description

Method of preparation of combined phosphorus fertilizer and soil improver 7 3 6 5 9

Phosphorus from phosphorus ores or their concentrates is insoluble or sparingly soluble and thus of limited use to plants. In the production of phosphorus fertilizers, the goal is to increase the phosphorus solubility of phosphorus ores. The solubility of phosphorus in a fertilizer is usually determined as the proportion of water-soluble, ammonium citrate-soluble or 2% citric acid-soluble phosphorus in the fertilizer as a proportion of total phosphorus. The most common method of preparing a phosphorus fertilizer is to treat the phosphorus ore with an inorganic acid, in which case the reaction product obtained may in itself be a phosphorus compound suitable for fertilization or may be further processed.

Another method of preparing phosphorus fertilizers is the heat treatment of phosphorus ore at high temperature with certain other substances.

Phosphorus fertilizer is also obtained from phosphorus-containing iron-20 ore as a by-product of the steel industry.

Phosphorus fertilizers obtained as a reaction product of phosphorus ore and inorganic acid have been prepared by hitherto known methods as follows: When sulfuric acid is used to treat phosphorus ore, a mixture of monocalcium phosphate and calcium sulphate (gypsum) called super phosphate is obtained as reaction product:

Ca2 (PO2) 2 gCaF2 + 7 H2SO4 ——> 30 phosphorus ore sulfuric (fluoroapatite) acid 3 Ca (H2PO4) 2 + 7 CaSO4 + 2 HF 1 monocalcium calcium fluorophosphate sulphate hydrogen

The superphosphate contains about 8% phosphorus, of which at least 93% is water-soluble.

73659

When tricalcium phosphate of phosphorus ore is reacted with sulfuric acid and water, the reaction product is phosphoric acid and calcium sulphate: 5 Ca3 (PO4) 2 + 3 H2SO4 + 6 H2O -> 3 CaSO4 * 2 H2O + 2 H2O04

Phosphoric acid is still used in the manufacture of phosphorus fertilizers such as double superphosphate and ammonium phosphates.

10 The reaction product of phosphorus ore and phosphoric acid is a double superphosphate which is almost pure monocalcium phosphate:

Ca3 (PO4) 2 3 * CaF2 + 14 H3PO4 -> 10 Ca (H2PO4) 2 + 2 HF i 15

The double superphosphate contains about 22% phosphorus, of which at least 93% is water soluble.

The reaction of phosphorus ore and hydrochloric acid results in dicalcium phosphate (CaHPO 4), which is of minor importance as a fertilizer.

The reaction product of phosphorus ore and nitric acid is a mixture of monocalcium phosphate and calcium nitrate. After removal of the calcium nitrate, the final product contains mono-calcium phosphate and dicalcium phosphate and nitrogen is added to the final product as ammonia.

The N: P fertilizer is usually 1: 0.44 to 1: 1.3 and contains 0 to 80% water-soluble phosphorus, depending on the preparation method.

Phosphorus fertilizer prepared by heat treatment is e.g. 30 rhenane phosphate prepared by heating a mixture of phosphorus ore, sodium carbonate and quartz sand at 1200 ° C: " 73659

Rheanania phosphate contains 11% phosphorus, which is soluble in basic ammonium citrate.

Tuomas slag is obtained from phosphorus-containing iron ore as a by-product of the steel industry. Limestone and oxygen are added to the molten iron ore 5, whereby the slag separates on the surface of the mixture.

Thomas slag contains 7-10% phosphorus, 90% of which is soluble in 2% citric acid.

The treatment of phosphorus ore with sulfuric acid is a very complex, high-precision, high-pressure process that requires a great deal of energy. The process produces hydrogen fluoride, which is toxic. Sulfuric acid is not only toxic but also expensive because its manufacturing process is complex and energy intensive. Although the superphosphate contains calcium sulphate, the process also leaves a large amount of calcium sulphate waste. This gypsum waste is an environmental nuisance. When treating phosphorus ore with sulfuric acid and water to obtain phosphoric acid, the disadvantages are otherwise the same as above, but gypsum waste is now generated even more abundantly. During the process, valuable trace elements and lanthanides are also lost.

The use of phosphoric acid as a fertilizer is, as such, so cumbersome that it is essentially a semi-finished product. It is thus used, as described above, e.g. for the manufacture of double super-phosphate and compound fertilizers.

Very few reactions are used between phosphorus ore and hydrochloric acid or nitric acid.

30 In the phosphorus ore heat treatment method, the phosphorus ore constituents remain in the fertilizer. However, the required temperature, 1200 ° C, is very high, so the energy consumption is high. Phosphorus is also not obtained in a water-soluble form.

35 Thomas slag is one of the oldest phosphorus-containing fertilizers. However, it only occurs in the context of the steel industry if the iron ore is phosphorus-rich. In addition, the process causes significant odor nuisances.

4,73659

The invention according to application No. 851525 eliminates or decisively reduces the following disadvantages listed above: - remarkably low energy consumption 5 - no need for industrially produced inorganic acids - no environmental disadvantages such as toxic emissions, odors, waste generation - almost complete recovery of phosphorus ore nutrient fractions .

According to said application No. 851525, the phosphorus fertilizer and / or soil improver is made from crushed and screened or ground phosphorus ore at a temperature of 50 ° to 800 ° C. The reaction medium is a moist organic mass having a pH of less than 5 and a temperature of 50 ° to 120 ° C. The ore and the organic reaction mass are allowed to collide. The invention is mainly known from the aspects defined in the patent claim.

In the following, one application of the method according to the invention will be described in detail in reference to the accompanying figure. From your joy 1, fresh, non-composted bark waste or peat is fed to grinding 2. If instead of or in addition to the above, pulp or paper mill waste fiber or sawdust can be fed directly to the process from the tank 3. Waste fiber means water , a so-called nol lacquer fiber which contains mainly short wood fibers which cannot be used in the manufacture of cellulose or paper. It always also has a finely ground bark, the so-called kuorimujua. All of the masses listed above should be acidic, with a pH below 6, preferably below 5.5. Then, in the reaction furnace 4, the bark, peat, cellulosic waste or sawdust is heated to a temperature of 50 to 120 ° C, 35 to the higher the wetter the pulp, and to the lower the higher the temperature of the phosphorus ore. The process described above corresponds approximately to that used in FI patent application no. FI841230 "Method for preparing a fertilizer from wood ash and softwood bark or other wood waste", but differs from these in that the moisture content of the fresh organic pulp must be at least 40%. This claim is not applied for. no 5 FI841230 method inside. The method differs from the application FI851525 in terms of a higher pH value of organic pulp closer to neutral, both in that the paper mill waste fiber is also suitable as organic pulp. After the reaction furnace 4, phosphorus ore, which may be of pragmatic, metamorphic or sedimentary origin or concentrates of these ores, is introduced into the process in the following 10 ways. The ore is first fed to a grinding drum 2A, where a particle fraction of 0.02 ... 3 mm is obtained. The smaller the particle size, the greater the amount of water- and / or citric acid-soluble phosphorus in the fertilizer. The optimal size is 0.02 ... 1 mm. The crushed ore is then passed to a rotary heating furnace 4A having a surface temperature of about 80 ° C. The pulp thus quickly heats up to a temperature of 50 ... 800 ° C, with an optimum temperature of 400 ... 500 ° C. The height of the optimum temperature depends on the quality and humidity of the phosphorus ore. The closer to the optimum temperature, the higher the amount of water- and / or citric acid-soluble phosphorus. What is completely new in the invention is that if the citric acid solubility of the phosphorus malt-25 min is naturally moderately high at least 10% (2% citric acid), heating of the ore is not required, i. the phosphorus ore is added to the acidic organic mass heated to about 20 ° C. This is economically advantageous. In this case, the temperature of the organic reaction mass must be at least 70 ° when unheated phosphorus ore is added. The phosphorus ore mass and the organic reaction mass from the reaction furnace 4 are then allowed to collide and mix with each other. In general, the higher the temperature at which the phosphorus ore is formed, the higher the temperature must be used. In this case, the phosphorus ore or its concentrate decomposes either completely or partially due to the following factors: 6 73659 1. Since the pH of the organic mass is lower than that of the phosphorus ore or its concentrate, the pH in the mixture tends to equilibrium. The lower the pH of the organic pulp and the higher the amount of water- and / or citric acid-soluble phosphorus in the fertilizer, the stronger the chemical reaction between the organic pulp and the phosphorus ore.

2. As the calcium and phosphorus content of the organic pulp is lower than that of the phosphorus ore, the lower the calcium and phosphorus content of the organic pulp, the lower the water and / or citric acid soluble phosphorus in the fertilizer.

The weight-15 ratio of dry phosphorus ore to fresh organic mass is 0.015 ... 0.65. The higher the organic mass, the higher the proportion of phosphorus in the phosphorus ore or concentrate obtained in water- and / or citric acid-soluble form. The time required for the reaction is 10..60 min, usually about 15 min. The longer the reaction time, the greater the proportion of phosphorus in the phosphorus ore or concentrate thereof obtained in water and / or citric acid soluble form. In addition to the organic wastes listed above - peeling waste, peat, cellulose or paper mill waste fiber, sawdust, 25 other similar organic pulps can also be used as reagents.

After the reaction, the mass is rapidly cooled in a condenser 5 to 20-40 ° C.

Finally, if necessary, wood or bark ash from tank 6 or nitrogen from tank 7 can be added to the product, the pulp 30 is granulated with rollers 8 if desired and ash can be added to the surface of the granules in mixer 9, as also described in the above-mentioned so-called FI841230.

The process according to the invention thus mimics the natural weathering of phosphorous ore. The water and / or citric acid solubility of the phosphorus in the fertilizer is 0 to 95%, depending on the amount and properties of the organic mass and phosphorus and the reaction time. The resulting aqueous

II

The 7,73659 soluble phosphorus compound is monocalcium phosphate (Ca (K 2 PO 2) 2) or a phosphate of its type. Energy consumption is low because the reaction takes place at a low temperature and because the organic reaction mass does not need to be prepared industrially. There are no environmental disadvantages; on the contrary, the process utilizes environmentally harmful organic waste. The nutrient fractions of phosphorus are recovered more completely than with inorganic acids, as well as with heat treatment methods.

The combined phosphate fertilizer and soil improver according to the invention can also be used as a roofing agent, if desired. In this case, the solubility of the phosphorus is of no practical significance. Thus, the content of phosphorus soluble in water and / or citric acid may be low in the pulp and the preparation may be simplified: the reaction time may be short and the heating temperature of the phosphorus soil may be low, or if the citric acid solubility of the phosphorus soil is at least 10%, heating may be omitted.

Claims (13)

1. Method of production of combined phosphorus fertilizer and soil improvement agent, wherein the fertilizer is made of crushed, saturated or ground phosphorous ore by means of an acidic reactant at a certain temperature, the reaction substance being such that it reacts with phosphorous ore, characterized by , that the acid, pH below 6, heist below 5.5, and humidity, humidity at least 40%, heist at least 45%, the reaction substance is organic, and that its calcium and phosphorus content is less than that of phosphorus ores, and that the particle fraction of phosphorus is 0, 02 ... 3 mm, heist 0.02 ... 1 mm, and when the organic reaction mass and the phosphorus ore collide and mix with each other, the temperature of the phosphorus ore is 20 ° ... 800 ° C and the organic mass temperature 50 ° ... 120 ° C, however il. 11 7 365 9 says that the temperature of the rana is about 20 ° C, the temperature of the organic race is at least 70 ° C. 2. A method according to claim 1, characterized in that when the citric acid solubility of the phosphorus ore of phosphorus 5 is at least IC%, the phosphorus ore is added unheated in the organic reaction substance, whose pH is below 6, the humidity at least 40% and the temperature 70 ° ... 120 ° C. . 3. Method of production of combined phosphorus fertilizer and soil improvement agent according to claim 1 or 2, characterized in that the temperature of the phosphorus ore is at least 50 ° C and that the organic reaction substance consists of bark waste, the temperature of which is at least 50 ° C, and of the citric acid solubility. of the phosphorus ore phosphorus Mr at least 10%, the ore is not heated and the temperature of the organic reaction substance is at least 70 ° C. 4. Method of production of combined phosphorus fertilizer and soil improvement agent according to claim 1 or 2, characterized in that the temperature of the phosphorus ore is at least 50 ° C and that the organic reaction substance is made of peat, whose temperature is at least 50 ° C, and if the citric acid solubility of the phosphorus ore phosphorus is at least 10%, it is unpopulated but not, and the temperature of the organic reaction agent is at least 70 ° C. 5. Method of production of combined phosphorus fertilizer and soil improvement agent according to claim 1 or 2, characterized in that the temperature of the phosphorus ore is at least 50 ° C, and the organic reaction substance consists of waste fiber from cellulose or paper mill, which is at least the temperature of waste fiber. 50 ° C, and if the citric acid solubility of the phosphorus ore phosphorus is at least 10%, the ore is not heated, and the temperature of the organic reaction agent is at least 7 ° C. 6. Method of production of combined phosphorus fertilizer and soil improvement agent according to patent; Claims 1 or 2, characterized in that the temperature of the foil ore is at least 50 ° C, and the organic reaction substance consists of sawdust, the temperature of which is at least 50 ° c. and if citrons are concerned, the phosphorus is high - at least phosphorus is at least