CN1202474A

CN1202474A - Neutral calcium superphosphate and its producing method

Info

Publication number: CN1202474A
Application number: CN 98112490
Authority: CN
Inventors: 李友朋
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-05-21
Filing date: 1998-05-21
Publication date: 1998-12-23

Abstract

Phosphorate rock, ardealite, lime stone and other material are mixed in certain order and reacted completely to produce the neutral calcium superphosphate. The product has low free acid and water content and can be mixed directly with urea to compound composite fertilizer without adhering. The production process has low sulfuric acid consumption, high phosphate rock conversion rate, low cost and less environmental pollution.

Description

Neutral calcium superphosphate and its production process

The invention relates to a production method of an agricultural fertilizer.

At present, the production of calcium superphosphate is obtained by decomposing phosphate rock powder by sulfuric acid, and the phosphate rock powder mainly contains Ca₅F(PO₄)₃、SiO₂The components are equal, a large amount of fluorine-containing gas is generated in the decomposition process, the fluorine-containing gas is recycled and processed into the fluorine salt by a manufacturer by adding salt water, and the chemical reaction equations of the fluorine-containing gas and the salt are as follows:

…(1)

………(2)

……(3)

……(4)

the calcium superphosphate product prepared by the method contains higher free acid and more water, the conversion rate of phosphorite is low, the phosphorite resource waste is large, the cost is high, in the process of recovering fluorine-containing gas, fluorine absorption equipment is blocked, fluorine absorption is incomplete, equipment is corroded, the treatment and recovery are not thorough, more fluosilicic acid is still used as waste water to be discharged, and waste water is discharged after the absorbed fluosilicic acid is prepared into villiaumite, which can cause serious pollution to the environment. In addition, a large amount of free acid contained in the calcium superphosphate product produced by the method reacts with urea when being mixed, so that more water is generated, and the mixed material is changed into a wet slurry together with the water originally existing in the original product, so that the application is inconvenient, and farmers cannot prepare the calcium superphosphate by themselves. If the compound fertilizer is prepared by a special manufacturer, the equipment is seriously blocked, the time for stopping and clearing the moisture is long, the preparation difficulty and the production cost are increased, and the compound fertilizer is not easy to prepare by mixing with urea.

The invention aims to provide neutral calcium superphosphate and a production method thereof, so that the produced product has low free acid content, less moisture, high phosphorite conversion rate, phosphorite resource saving, cost saving, high fertilizer efficiency, convenient mixing, preparation and application with urea, no wet sludge slurry and greatly reduced environmental pollution.

The purpose of the invention is realized as follows: adding sulfuric acid into the phosphate rock powder, fully mixing, fully reacting to obtain cured clinker, adding phosphogypsum and calcium powder into the clinker, further reacting, recovering fluosilicic acid generated when the sulfuric acid decomposes the phosphate rock powder, further preparing calcium dihydrogen phosphate and fluosilicic acid, and repeating the steps until the fluosilicic acid is absorbed to be clean, thereby further improving the yield of the finished product. Their chemical reaction equation is as follows:

…(5)

………(6)

……(7)

…(8)

………(9)

……(10)

it can be seen from the chemical reaction equations (5), (6) and (7) that after sulfuric acid is added to the powdered rock phosphate, hydrogen fluoride gas is generated, which reacts with silicon dioxide to generate silicon fluoride gas, and silicon fluoride reacts with water to generate fluorosilicic acid. It can be seen from the chemical reaction equations (8), (9) and (10) that the generated fluosilicic acid continuously reacts with the phosphate rock to further generate the main component monocalcium phosphate of the phosphate fertilizer, and the cycle repeats, so that the fluosilicic acid is absorbed to the maximum extent, the pollution components of the environment are reduced, the purity of the phosphate fertilizer is improved, and the fluosilicic acid is recycled to reduce the consumption of sulfuric acid and environmental pollution.

The production steps of the invention are as follows:

a. and (4) crushing the phosphate ore until the phosphate ore is crushed into mineral powder or ore pulp.

b. A certain amount of mineral powder or ore pulp and a proper amount of sulfuric acid are respectively fed into a mixer to be mixed, and after a violent chemical reaction is generated, the obtained slurry is fed into a formation chamber to be solidified.

c. After the curing in the formation chamber, the materials are cut up by a cutting machine and then discharged from the formation chamber to be conveyed to a curing warehouse by a belt conveyor for further reaction and curing, and a semi-finished product is formed.

d. Then adding a certain amount of phosphogypsum and limestone powder into the cured semi-finished product, turning the pile and continuously reacting to obtain a finished product.

e. And (c) after the fluorine-containing gas generated in the step (b) enters a fluorine absorption chamber to be absorbed into fluosilicic acid, pumping the fluosilicic acid into a mixer to be mixed and reacted with sulfuric acid and ground phosphate rock, and further recovering the fluosilicic acid.

f. And finally, after the fluosilicic acid and the fluorine-containing gas are almost absorbed, the remaining three wastes are discharged, and a finished product with higher quality is obtained.

The proportion of each component is as follows:

50 to 60 percent of phosphate ore and 30 to 35 percent of sulfuric acid

5 to 15 percent of phosphogypsum and 5 to 15 percent of limestone powder

Compared with the background technology, the invention has the following characteristics:

1. because the phosphogypsum and the limestone are mixed into the semi-finished product, the free acid and the moisture are greatly reduced, the problem of wetting when the phosphogypsum and the limestone are mixed into the compound fertilizer is solved, farmers can directly prepare the compound fertilizer, a plurality of faults are reduced for producing the compound fertilizer in factories, the effect is greatly improved, and the cost is saved.

2. The fluosilicic acid is recycled to decompose the powdered rock phosphate, so that part of sulfuric acid is replaced, the consumption of sulfuric acid is reduced, waste is changed into valuable, the minimum emission of three wastes is realized, the environmental pollution is greatly reduced, and the rock phosphate resource is saved.

The first embodiment is as follows:

preparing raw materials according to the production steps to produce 1 ton cost phosphate fertilizer, wherein the required weight of each component is as follows:

500kg of phosphate ore and 300kg of sulfuric acid

150kg of phosphogypsum and 150kg of limestone powder

Example two:

the production steps are the same as the above, and 1 ton of finished phosphate fertilizer is produced, and the required weight of each component is as follows:

600kg of phosphate ore and 350kg of sulfuric acid

50kg of phosphogypsum 50kg of limestone powder 50kg

Example three:

the production steps are as above: 1 ton finished phosphate fertilizer is produced by the followingcomponents by weight:

550kg of phosphate ore and 330kg of sulfuric acid

100kg of phosphogypsum and 80kg of limestone powder

In the three embodiments, the purpose of producing finished products of phosphate fertilizers can be achieved.

Claims

1. The production method of neutral calcium superphosphate is characterized by comprising the following production steps:

2. The neutral calcium superphosphate is characterized by comprising the following components in percentage by weight:

50-60% of phosphate ore and 30-35% of sulfuric acid

5-15% of phosphogypsum and 5-15% of limestone powder