Method of decomposing phosphate tailings by hydrochloric acid to produce Mg(OH)2 and CaSO4

A technology of magnesium hydroxide and phosphorus tailings, applied in the direction of magnesium hydroxide, calcium/strontium/barium sulfate, ammonium salt fertilizers, etc., can solve problems such as low quality, restriction of compound fertilizer production capacity, and overcapacity, and achieve the production process Simple, low production cost, and the effect of reducing environmental pressure

Active Publication Date: 2017-03-15
HUBEI SANNING CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Hydrochloric acid is a by-product of compound fertilizer, which has low quality and excess production capacity, which seriously restricts the production capacity of compound fertilizer

Method used

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  • Method of decomposing phosphate tailings by hydrochloric acid to produce Mg(OH)2 and CaSO4

Examples

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Embodiment 1

[0032] Phosphorus tailings and water are made into a slurry at a mass ratio of 1:0.5, and hydrochloric acid is added to the leaching tank to fully mix and react. The ratio of the molar amount of hydrochloric acid to the sum of the molar amounts of CaO and MgO in the phosphorous tailings is 1.6:1 , control the reaction temperature at 30°C, react for 0.5h under the condition of sufficient stirring, filter and separate to obtain slag I and mother liquor I, add sulfuric acid with a molar ratio of CaO of 1:1 to the mother liquor I to react and crystallize, and then enter the filtration and separation. Wash the filter cake with water to obtain the product calcium sulfate whiskers and mother liquor II, add ammonia water to the mother liquor II for two-stage neutralization, one-stage neutralization to control the pH to 2.5, filter and separate slag II and mother liquor III, and perform two-stage neutralization for mother liquor III , control the pH to 6.5, filter and separate to obtain...

Embodiment 2

[0035] Phosphorus tailings and water are made into a slurry at a mass ratio of 1:0.7, and hydrochloric acid is added to the leaching tank to fully mix and react. The ratio of the molar amount of hydrochloric acid to the sum of the molar amounts of CaO and MgO in the phosphorous tailings is 1.8:1 , control the reaction temperature at 30°C, react for 0.5h under the condition of sufficient stirring, filter and separate to obtain slag I and mother liquor I, add sulfuric acid with a molar ratio of CaO of 1:1 to the mother liquor I to react and crystallize, and then enter the filtration and separation. Wash the filter cake with water to obtain the product calcium sulfate whiskers and mother liquor II, add ammonia water to the mother liquor II for two-stage neutralization, one-stage neutralization to control the pH to 3.0, filter and separate slag II and mother liquor III, and carry out two-stage neutralization for mother liquor III , control the pH to 7.0, filter and separate to obta...

Embodiment 3

[0038] Phosphorus tailings and water are made into a slurry at a mass ratio of 1:0.8, and hydrochloric acid is added to the leaching tank to fully mix and react. The ratio of the molar amount of hydrochloric acid to the sum of the molar amounts of CaO and MgO in the phosphorous tailings is 1.7:1 , control the reaction temperature at 30°C, react for 0.5h under the condition of sufficient stirring, filter and separate to obtain slag I and mother liquor I, add sulfuric acid with a molar ratio of CaO of 1:1 to the mother liquor I to react and crystallize, and then enter the filtration and separation. Wash the filter cake with water to obtain the product calcium sulfate whiskers and mother liquor II, add ammonia water to the mother liquor II for two-stage neutralization, one-stage neutralization to control the pH to 3.0, filter and separate slag II and mother liquor III, and carry out two-stage neutralization for mother liquor III , control the pH to be 7.5, filter and separate to o...

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Abstract

The invention belongs to the field of chemical engineering and particularly relates to a method of decomposing phosphate tailings by hydrochloric acid to produce Mg(OH)2 and CaSO4. The method includes the steps of: soaking the phosphate tailings in hydrochloric acid and water to perform a complete mixing reaction, and performing primary filtration to obtain a mother liquid (I); adding diluted sulfuric acid to the mother liquid (I) and performing secondary filtration to obtain a mother liquid (II) and filter cake, water-washing and crystallizing the filter cake to generate CaSO4 crystal whiskers; adding ammonia water to the mother liquid (II) to perform primary and secondary neutralization to obtain a Mg(OH)2 product and a mother liquid (IV); and mixing the mother liquid (IV) with residue (II), which is generated in primary neutralization, to produce ammonium chloride-phosphate. With the phosphate tailings and hydrochloric acid as raw materials, the method can produce the Mg(OH)2 and CaSO4 and can by-produce the ammonium chloride-phosphate. The whole process is simple and is in a total-closed circulating manner. The method can turn waste into resources and achieves clean production.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a method for preparing magnesium hydroxide and calcium sulfate by decomposing phosphorus tailings with hydrochloric acid. Background technique [0002] my country's phosphate rock reserves are relatively abundant, but most of them are low-grade ore, and most of them are refractory minerals. As a large agricultural country, phosphate rock resources are widely used in the production of agricultural chemical fertilizers. Phosphorus resources have shifted from high-grade ore mining to low-grade lean ore mining, resulting in a large amount of phosphorus tailings. The accumulation of phosphorus tailings not only leads to waste of resources, but also produces serious environmental pollution. The effective elements of calcium, magnesium and phosphorus in phosphorus tailings still account for a relatively large proportion, and their recycling and turning waste into ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F5/20C01F11/46C05G1/00
CPCC01F5/20C01F11/46C01P2006/80C05B11/12C05B17/00C05C3/00
Inventor 肖林波田承涛方超李攀红文家武徐思红
Owner HUBEI SANNING CHEM
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