CN101041603A - Preparation technical method of urine sulfur radical composite fertilizer - Google Patents

Abstract

The invention discloses a process method for producing urea-sulfur-based compound fertilizer, which mainly includes the following process steps: (1) adding sulfuric acid and phosphate rock determined according to the design ratio of phosphorus and sulfur components of the compound fertilizer product into an acidolysis reactor Acid hydrolysis reaction to prepare acid hydrolysis slurry; (2) adding urea and acid hydrolysis slurry determined according to the design ratio of nitrogen, phosphorus and sulfur components of the compound fertilizer product into the conversion reactor for conversion reaction to prepare conversion slurry; ( 3) Perform product solidification treatment on the conversion slurry to produce urea-sulfur-based compound fertilizer products. The invention uses phosphate rock as the phosphorus source, has low raw material cost, and does not have the problem of phosphogypsum stacking; the prepared compound fertilizer contains part of the slow-release fertilizer component, and the fertilizer efficiency utilization rate is high; the production process is simple, and the equipment investment is low. The invention can use phosphate rock with poor reactivity to produce urea-sulfur-based compound fertilizer, and is a new process for producing compound fertilizer based on ordinary calcium and ammonium phosphate.

Description

Preparation method of urea-sulfur-based compound fertilizer

Technical field:

The invention relates to the preparation technology of compound fertilizer, more specifically, relates to a preparation technology of urea-sulfur-based nitrogen-phosphorus compound fertilizer.

Background technique:

Crop growth requires 16 essential nutrients, among which nitrogen, phosphorus, and potassium rank the top three in terms of importance. According to China's soil conditions, the ratio of nitrogen, phosphorus and potassium fertilizers required for crop growth is roughly 2:1:1, but in China's agricultural production and fertilization, the ratio of nitrogen (N), phosphorus (P), and potassium (K) fertilizers has been out of balance for a long time , which is lower than a reasonable level. The reason is that in addition to the low yield of potassium fertilizer, there is also a lack of production technology for compound fertilizers that can simultaneously provide nitrogen, phosphorus, potassium and other nutrients. Ammonium phosphate is a nitrogen-phosphorus compound fertilizer that is currently used in a relatively large amount, but the N in ammonium phosphate is generally 10% to 18%, and the P2O5 is generally 46% to 52%. It is generally regarded as a phosphate fertilizer. In addition, in ammonium phosphate Sulfur and calcium elements have been removed during the production process, therefore, ammonium phosphate cannot really provide nitrogen and phosphorus compound fertilizers containing sulfur and calcium nutrients that meet the needs of agricultural production. In order to meet the needs of crop growth for nitrogen, potassium, sulfur and calcium elements Nutrient needs, often need to add additional nitrogen, potassium, calcium and sulfur nutrients. The relatively simple way of producing nitrogen-phosphorus compound fertilizers containing sulfur and calcium nutrients in the prior art is to produce them with urea and common calcium superphosphate (abbreviated as calcium superphosphate). It is cheap and already contains sulfur and calcium elements, so the nitrogen-phosphorus compound fertilizer produced contains more comprehensive nutrients and lower cost. However, in the process of producing compound fertilizer with urea and calcium superphosphate, a large amount of crystal water and free water will be released after the reaction of urea and calcium superphosphate, and the reactant will become thin mud with extremely poor physical properties. Therefore, urea and ordinary calcium superphosphate are difficult to be compatible, and generally need to be neutralized before mixing. The French Sophia-Antipolis Research Center found that the complex formed by urea and sulfuric acid can continue to leach tricalcium phosphate. This achievement was adopted by the largest French fertilizer production company (Grande Paroisse). The main process steps of the production method are: first mix urea and sulfuric acid in a fixed ratio (such as the molar ratio of urea and sulfuric acid is 1.6:1 or 3.6:1) to form sulfuric acid urine, then react with phosphate rock, and then carry out chemical conversion with ripening. The production process of urea general calcium developed by Grande Paroisse company in France can avoid the problem of poor physical properties of the produced compound fertilizer, and can obtain the expected ratio of nitrogen and phosphorus. Scientific research institutes such as China Shanghai Research Institute of Chemical Industry and Sichuan University have also carried out research on the production process of calcium urea, and achieved some results, but there is no industrialization so far. The conversion rate of phosphorus is relatively low (generally below 10%), and it is difficult to solidify at the same time, so it is difficult to adapt to many phosphate rocks in our country.

Contents of the invention

Aiming at the problems existing in the preparation process of urea-sulfur-based compound fertilizer in the prior art, the object of the present invention is to provide a novel method for preparing urea-sulfur-based compound fertilizer, so as to solve the problems existing in the preparation process of urea-sulfur-based compound fertilizer in the prior art. The conversion rate of phosphorus in phosphate rock is low and the product is difficult to solidify, and the compound fertilizer produced has an ideal ratio of nitrogen to phosphorus, rich in sulfur and calcium elements, and there is no problem of phosphogypsum emission during the production process. Between ordinary calcium and conventional urea ordinary calcium process, it can be directly granulated and potassium element can be added during production, and the production cost is relatively low.

The process for preparing urea-sulfur-based compound fertilizer disclosed by the present invention combines the production method of ordinary calcium superphosphate and the production method of French urea general calcium, absorbs the advantages of both, and avoids the disadvantages of both.

The preparation process of urea-sulfur-based compound fertilizer disclosed by the present invention mainly includes the following sequential process steps:

1. Put sulfuric acid and phosphate rock in an amount determined according to the design ratio of phosphorus and sulfur components of the compound fertilizer product into the acidolysis reactor, and carry out acidolysis reaction on the phosphate rock to prepare acidolysis slurry;

2. Add the urea and acid hydrolysis slurry determined according to the design ratio of the nitrogen, phosphorus and sulfur components of the compound fertilizer product into the conversion reactor to carry out the urea conversion reaction to prepare the conversion slurry;

3. Perform product solidification treatment on the conversion slurry to produce urea-sulfur-based compound fertilizer products.

In the acid hydrolysis reaction process of sulfuric acid acid hydrolysis phosphate ore of above-mentioned technical scheme, the present invention has fully utilized the reactivity of hydrogen ion, and the higher temperature that heat of reaction produces, has strengthened the acid hydrolysis reaction process, makes in this operation The following main reactions are fully carried out:

Ca ₅ (PO ₄ ) ₃ F+5H ₂ SO ₄ +2.5H ₂ O→3H ₂ PO ₄ +CaSO ₄ 1/2H ₂ O+HF

Ca ₅ (PO ₄ ) ₃ F+7H ₃ PO ₄ +5H ₂ O→5Ca(H ₂ PO ₄ ) ₂ +HF

2Ca ₅ (PO ₄ ) ₃ F+7H ₂ SO ₄ +6.5H ₂ O→3Ca(H ₂ PO ₄ ) ₂ ·H ₂ O+7CaSO ₄ ·1/2H ₂ O+2HF

In the conversion reaction process of converting urea into ammonium sulfate in the above-mentioned technical scheme, the acid hydrolysis slurry reacts with urea to make urea generate urea double salts including urea gypsum, wherein a small part of urea is converted into ammonium sulfate, and the total Nitrogen loss is minimal. In this process, the following reactions mainly occur:

CaSO ₄ 1/2H ₂ O+4CO(NH ₂ ) ₂ →CaSO ₄ 4CO(NH ₂ ) ₂ +1/2H ₂ O

H ₂ SO ₄ +2H ₂ O+CO(NH ₂ ) ₂ →(NH ₄ ) ₂ SO ₄ ·H ₂ O+CO ₂ ↑

Ca(H ₂ PO ₄ ) ₂ ·H ₂ O+4CO(NH ₂ ) ₂ →4Ca(H ₂ PO ₄ ) ₂ ·CO(NH ₂ ) ₂ +H ₂ O

After the conversion slurry coming out of the conversion reactor is solidified, a variety of double salt crystals are obtained, and a nitrogen-phosphorus compound fertilizer with good physical properties is prepared. There are two ways to produce urea-sulfur-based compound fertilizer products by curing the conversion slurry from the conversion reactor. One is that the conversion slurry from the conversion reactor first enters the aging device for aging and curing treatment. Then use a crusher to break into urine-sulfur-based compound fertilizer products; the other is to use a spray gun to spray the conversion slurry from the conversion reactor into a granulator for granulation to produce urine-sulfur-based compound fertilizer products. When the latter is used for product solidification, potassium salt can also be added at the same time during the curtain granulation process where the conversion slurry is directly sprayed into the granulator and picked up by the lifting board, and the production of multi-component compound fertilizer can be completed in one step. The compound fertilizer product prepared by solidifying the conversion slurry from the conversion reactor, wherein the water-soluble phosphorus can account for more than 90% of the available phosphorus, and the conversion rate of the phosphate rock can reach 82% to 95%.

For the process of solidifying the conversion slurry with an aging device, during the acid hydrolysis reaction process of acid hydrolyzing phosphate rock with sulfuric acid, the phosphate rock can be added to the acid hydrolysis reactor in the form of phosphate rock slurry, and sulfuric acid and phosphate rock are added to it at the same time . The acidolysis reaction of phosphate rock and sulfuric acid can be carried out at the ambient temperature formed by the heat of acidolysis reaction, and the reaction temperature is generally 90-140°C. The converted slurry enters the conversion reactor and reacts with urea, and the reaction temperature can generally be controlled at 60-90°C. The converted slurry after the reaction enters the aging tank and can be solidified at a temperature of 50-80°C. In the conversion reactor, the ratio of urea to added sulfuric acid can be adjusted according to the design ratio of the nutrient components of the compound fertilizer product, not necessarily limited to the ratio (such as 3.6:1 or 1.8:1) commonly used for calcium urea. In order to strengthen the reaction, an activator can be added to the acidolysis reactor and conversion reactor. The activator can be added in only one reaction or in two reactions at the same time. Commonly used activators include nitric acid, hydrochloric acid, KCI, laurylamine polyoxyethylene ether-12, dimethyl alkyl brominated hydrocarbons, cationic 12-carbon oil and so on. The solids from the aging device can be packaged after crushing.

For the product curing process of conversion slurry by spray granulation, the process flow is similar to the process flow of product curing conversion slurry by aging device, mainly the product curing method is different. The conversion slurry from the conversion reactor is sprayed into the spray granulator on the material curtain lifted by the lifter with a spray gun, the slurry is coated on the surface of the particles, and the particles are bonded to each other to form agglomerates during rolling. In the granulator, a higher temperature bar is conducive to the solidification of the granules, and the solidification is faster, but if the temperature is too high, it will cause the decomposition of urea, so the temperature should be avoided too high, and the moderate temperature of the granulator should not be higher than 200 ° C. . In the granulation process of the granulator, potassium salt can be added to produce multiple compound fertilizers, and appropriate additives can be added to adjust the nutrients of the fertilizer, or adjust the pH value, or enhance isolation to avoid bonding, such as adding calcium carbonate, gypsum and other additives .

The urea-based compound fertilizer (MUSP) based on nitrogen and phosphorus and the urea-based compound fertilizer (MUSPK) based on nitrogen, phosphorus and potassium produced by the method of the present invention are novel compound fertilizers containing nitrogen, phosphorus, potassium, sulfur, etc. Various elements. However, ordinary calcium superphosphate has a single nutrient, and after it is applied to the ground, the fertilizer utilization rate is poor due to the degradation of phosphorus. If urea and ordinary calcium superphosphate are used as raw materials to produce nitrogen-phosphorus fertilizer (NP) and nitrogen-phosphorus-potassium fertilizer (NPK), due to the extremely poor physical properties during mixing, ordinary calcium will release water during the granulation process, making the return of NPK during the granulation process If the material ratio is too high, the energy consumption of the drying process is high, and it is easy to agglomerate. One of another feature of the present invention is that urea and general calcium are compounded in the production process, which can produce nitrogen, phosphorus, and potassium components in multiple ratios (20-10-0, 15-10-10, 20-10-10 ) compound fertilizer. Compared with the traditional process of producing compound fertilizer with urea, ammonium sulfate, phosphoric acid and ammonia as raw materials, the cost can be reduced by 10-30%. The invention directly uses phosphate rock as raw material, and there is no problem of phosphogypsum pollution. At the same time, it can use the remaining tailings after the iron ore beneficiation in my country, so it has good economic and social benefits. The main advantages of this process are:

(1) The source of phosphorus is phosphate rock, the cost is lower than that of ammonium phosphate, and there is no problem of phosphogypsum stacking.

(2) The prepared compound fertilizer contains some slow-release fertilizer components, so the utilization rate of the fertilizer is improved.

(3) The amount of fluorine gas discharged is lower than that of ordinary calcium superphosphate production process.

(4) The production process is relatively simple, the cost is low, the investment in equipment is low, and phosphate rock with poor reactivity can be used. It is one of the new methods to replace ordinary calcium and produce compound fertilizer based on ammonium phosphate.

Description of drawings

Accompanying drawing 1 is the technological process of an embodiment of the present invention.

Accompanying drawing 2 is the technological process of another embodiment of the present invention.

Accompanying drawing 3 is the process flow of another embodiment of the present invention.

Accompanying drawing 4 is the technological process of yet another embodiment of the present invention

Detailed ways

The examples given below are specific descriptions of the present invention. It is necessary to point out that the following examples are only used to further illustrate the present invention, and can not be interpreted as limiting the protection scope of the present invention. Those skilled in the art according to the above-mentioned The content of the present invention The non-essential improvements and adjustments made to the present invention still belong to the protection scope of the present invention.

In the following examples, unless otherwise specified, the parts of each component are parts by weight, and the percentages of each component are percentages by weight.

Example 1

The process flow of this embodiment is shown in Figure 1. The raw material is phosphorus tailings obtained from Liaoning phosphate iron ore after iron separation, and the P ₂ O ₅ is about 30%. 100 parts of phosphate rock powder and 30 parts of water are prepared into phosphate rock slurry, and 40 parts of sulfuric acid with a concentration of 90% are added to acidolysis reactor 1 for acidolysis reaction, and 2 parts of activator dimethyl alkyl brominated agent are added, The reaction temperature is about 130° C., and the reaction time is about 30 minutes. The add-on of sulfuric acid all can be in the scope of 40～80 parts. The fluorine gas produced in the acidolysis reaction enters the fluorine recovery device, and fluorine is recovered in the form of fluorosilicate, and the acidolysis slurry after the reaction enters the conversion reactor 2, and 110 parts of urea are added at the same time to carry out the conversion reaction, and an activator is added 1 part of cationic 12-carbon oil agent, the conversion reaction temperature is about 80°C, and the reaction time is about 40 minutes. The conversion slurry from the conversion reactor enters the aging device for aging and solidification reaction. The aging temperature is about 60°C and the aging time is about 10 hours, usually 8-16 hours. The cured fertilizer is relatively loose, and it can be crushed with a crusher to obtain the finished urea-sulfur-based compound fertilizer. The ratio of nitrogen, phosphorus and potassium in compound fertilizer is about 1.8:1:0. The conversion rate of phosphate rock in this embodiment is about 90%.

Example 2

The process flow of this embodiment is shown in Figure 2. The raw material is still phosphorus tailings with a P2O5 content of about 30% obtained after iron separation from Liaoning phosphate iron ore. The process and process conditions of this embodiment are basically the same as in Example 1, except that the acidolysis reaction and conversion reaction do not add an activator to strengthen the reaction, the reaction time is longer, and the acidolysis reaction time is about 30 ~45 minutes, the conversion reaction time is about 45~60 minutes, and the aging time is about 17 hours, usually 16~20 hours. The conversion rate of phosphate rock is lower, and the conversion rate of phosphate rock in this embodiment is about 80%.

Example 3

The process flow of this embodiment is shown in Figure 3. The raw material is Sichuan Jinhe phosphate rock with a P ₂ O ₅ content of 28%. 100 parts by weight of phosphate rock powder, 70 parts of water, 70 parts of sulfuric acid with a concentration of 98%, 2 parts of activator nitric acid, all materials are added to acid hydrolysis reactor 1 for acid hydrolysis reaction, the reaction temperature is about 100 °C, and the reaction time is about 20 minute. The add-on of sulfuric acid all can be in the range of 30～70 parts. The fluorine gas produced in the acidolysis reaction enters the fluorine recovery device, and fluorine is recovered in the form of fluorosilicate. The acidolysis slurry after the reaction enters the conversion reactor 2, and 110 parts of urea are added at the same time, and the activator laurylamine polyoxygen Vinyl ether - 2 parts by weight of 12, the conversion reaction temperature is about 50°C, and the reaction time is about 45 minutes. The conversion slurry coming out of the conversion reactor 2 is sprayed into the material curtain lifted by the lifting plate in the granulator with a spray gun for granulation. The temperature of the hot air entering the granulator is about 180°C, and the temperature of the hot air outlet is about Around 80°C. Add 40 parts of potassium chloride containing 60% _K2O from the head of the granulator, and add 3 parts of spacer and neutralizer calcium carbonate powder from the tail of the granulator. The granular fertilizer discharged from the outlet of the granulator is the finished MUSPK compound fertilizer after cooling. The ratio of nitrogen, phosphorus and potassium in compound fertilizer is about 2:1:1. The conversion rate of phosphate rock in this embodiment can reach about 90%.

Example 4

The process flow of this embodiment is shown in Figure 4. The raw material is still Sichuan Jinhe phosphate rock with a P ₂ O ₅ content of 28%. The process and process conditions of this embodiment are basically the same as those of Example 3, except that during the spray granulation process, potassium salt, release agent and neutralizing agent carbonic acid were not added to the head and tail of the granulator respectively. Calcium powder, the urine-sulfur-based compound fertilizer produced does not contain potassium nutrients, and the granular fertilizer discharged from the outlet of the granulator is the finished MUSP compound fertilizer after cooling.

Claims (10)

1, a kind of urea-sulfur-based compound fertilizer preparation process, is characterized in that comprising following successive process steps: (1) adding sulfuric acid and phosphate rock to the acidolysis reactor according to the design ratio of the phosphorus and sulfur components of the compound fertilizer product, and carrying out acidolysis reaction to the phosphate rock to prepare acidolysis slurry; (2) adding urea and acid hydrolysis slurry into the conversion reactor to carry out the urea conversion reaction according to the design ratio of nitrogen, phosphorus and sulfur components of the compound fertilizer product, to prepare the urea conversion slurry; (3) Perform product solidification treatment on the converted slurry to produce urea-sulfur-based compound fertilizer products. 2. The process for preparing urea-sulfur-based compound fertilizer according to claim 1, characterized in that the solidification treatment method of said urea conversion slurry product is that the conversion slurry coming out of the conversion reactor first enters the aging device for further processing. Aging and solidification treatment, after solidification, it is crushed by a crusher into urea-sulfur-based compound fertilizer products. 3. The process for preparing urea-sulfur-based compound fertilizer according to claim 2, characterized in that the aging and curing temperature for aging and curing the urea conversion slurry is 50-80°C, and the time is about 15-24 hours. Hour. 4. The process for preparing urea-sulfur-based compound fertilizer according to claim 1, characterized in that the solidification treatment method of the conversion slurry product is that the urea conversion slurry coming out of the conversion reactor is sprayed into granulation with a spray gun machine for granulation. 5. The process for preparing urea-sulfur-based compound fertilizer according to claim 4, characterized in that said spray granulation is to inject the urea conversion slurry into the spray granulator with a spray gun and pick it up by a lifting board Granulation is carried out on the material curtain. 6. The process for preparing urea-sulfur-based compound fertilizer according to claim 5, characterized in that during the process of spraying the urea conversion slurry into the granulator with a spray gun for granulation, the head of the granulator adds Fertilizer product nitrogen, phosphorus, sulfur, and potassium components are designed with a certain amount of potassium salt in the design ratio. 7. The process for preparing urea-sulfur-based compound fertilizer according to claim 5, characterized in that during the process of spraying the urea conversion slurry into the granulator with a spray gun for granulation, the conversion material is added from the tail of the granulator A defined amount of neutralizing and/or isolating agent. 8. The process for preparing urea-sulfur-based compound fertilizer according to claim 5, characterized in that the urea conversion slurry is sprayed into the granulator with a spray gun for granulation, and the temperature in the granulator is 150-180 ℃. 9. The process for preparing urea-sulfur-based compound fertilizer according to any one of claims 1 to 8, characterized in that an activator is added during the acidolysis reaction and/or the urea ammonium sulfate conversion reaction. 10. The process for preparing urea-sulfur-based compound fertilizer according to claim 9, characterized in that said activator is selected from nitric acid, hydrochloric acid, KCI, laurylamine polyoxyethylene ether-12, dimethyl alkyl bromide , Cationic 12 carbon oil.

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