Method for preparing calcium sulfate whiskers and magnesium hydroxide by decomposing phosphate tailings through hydrochloric acid

A calcium sulfate whisker and magnesium hydroxide technology, applied in the direction of magnesium hydroxide, magnesium chloride, magnesium halide, etc., can solve the problems of low quality, overcapacity, and restriction of compound fertilizer production capacity, and achieve simple production process, low production cost, The effect of reducing environmental pressure

Inactive Publication Date: 2017-08-29
HUBEI SANNING CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Hydrochloric acid is a by-product of compound fertilizer, which has low quality and exces...

Method used

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  • Method for preparing calcium sulfate whiskers and magnesium hydroxide by decomposing phosphate tailings through hydrochloric acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Add phosphorus tailings and hydrochloric acid (mother liquor) to the decomposition tank, control the amount of HCl in the leaching tank to be 2.0 times that of CaO and MgO in the input phosphorus tailings, the reaction temperature is 40°C, and the reaction time is 30 minutes. The reaction slurry is subjected to solid-liquid separation I to generate the first mother liquor containing calcium chloride and magnesium chloride, and the solid waste residue obtained after the first filter cake washing I is an acid insoluble matter.

[0030] Add sulfuric acid reaction crystallization to the first mother liquor containing calcium chloride and magnesium chloride, according to the total amount of Ca2+ in the mother liquor, the amount of sulfuric acid is 1.0 times of the Ca2+ content in the filtrate, and the liquid-solid ratio is controlled at 10:1 in the calcium sulfate crystallization process. And control the reaction temperature to 50° C. and the reaction time to 30 minutes to ob...

Embodiment 2

[0039] Add phosphorus tailings and hydrochloric acid (mother liquor) to the decomposition tank, control the amount of HCl in the leaching tank to be 2.5 times that of CaO and MgO in the input phosphorus tailings, the reaction temperature is 30°C, and the reaction time is 60 minutes. The reaction slurry is subjected to solid-liquid separation I to generate the first mother liquor containing calcium chloride and magnesium chloride, and the solid waste residue obtained after washing the first filter cake is an acid insoluble matter.

[0040] Add sulfuric acid reaction crystallization to the first mother liquor containing calcium chloride and magnesium chloride, according to the total amount of Ca2+ in the mother liquor, the amount of sulfuric acid is 1.0 times of the Ca2+ content in the filtrate, and the liquid-solid ratio is controlled at 20:1 in the calcium sulfate crystallization process. The reaction temperature was controlled at 40° C., and the reaction time was 60 minutes to...

Embodiment 3

[0049] Add phosphorus tailings and hydrochloric acid (mother liquor) to the decomposition tank, control the amount of HCl in the leaching tank to be 2.2 times that of CaO and MgO in the input phosphorus tailings, the reaction temperature is 40°C, and the reaction time is 60 minutes. The reaction slurry is subjected to solid-liquid separation I to generate the first mother liquor containing calcium chloride and magnesium chloride, and the solid waste residue obtained after the first filter cake washing I is an acid insoluble matter.

[0050] Add sulfuric acid reaction crystallization to the first mother liquor containing calcium chloride and magnesium chloride, according to the total amount of Ca2+ in the mother liquor, the amount of sulfuric acid is 1.0 times of the Ca2+ content in the filtrate, and the liquid-solid ratio is controlled at 8:1 during the calcium sulfate crystallization process. And control the reaction temperature to 50° C. and the reaction time to 60 minutes to...

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Abstract

The invention relates to a method for preparing calcium sulfate whiskers and magnesium hydroxide by decomposing phosphate tailings through hydrochloric acid. The method comprises the following steps: adding phosphate tailings and hydrochloric acid into a decomposing tank to adequately react in the decomposing tank, and carrying out solid-liquid separation I on reacted slurry, so as to separate first mother solution and solid waste residues, wherein the solid waste residues are acid-insoluble substances; adding sulfuric acid into the first mother solution to react for crystallization, so as to generate the calcium sulfate whiskers; carrying out solid-liquid separation on crystallized slurry, so as to separate calcium sulfate dihydrate whiskers, wherein the mother solution is a mixed mother solution containing magnesium chloride and hydrochloric acid; after magnesium chloride in the mixed mother solution reaches a certain concentration, starting to take out a part of mixed mother solution, carrying out flash evaporation to evaporate HCl in the mother solution so as to obtain the mother solution mainly containing magnesium chloride, and returning the rest part of the mixed mother solution to the decomposing tank; introducing ammonia gas into the magnesium chloride mother solution, and carrying out solid-liquid separation, so as to obtain a relatively pure magnesium chloride mother solution and magnesium ammonium chloride solids containing a small amount of impurities; and absorbing HCl gas in the front stage by a magnesium ammonium chloride solution to enable the pH value of the magnesium ammonium chloride solution to be close to neutrality, and carrying out concentration and crystallization, so as to obtain magnesium ammonium chloride crystals. The method has the advantage that magnesium hydroxide and the calcium sulfate whiskers which have relatively high quality can be produced from industrial waste and the cheap raw materials.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and relates to a method for decomposing phosphorus tailings with hydrochloric acid to produce calcium sulfate whiskers and magnesium hydroxide, specifically a method for decomposing phosphorus tailings with hydrochloric acid to obtain calcium chloride and magnesium chloride, and then combining sulfuric acid and ammonia Process for producing calcium sulfate whiskers and magnesium hydroxide. 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 wast...

Claims

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Application Information

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IPC IPC(8): C01F11/46C01F5/20C01F5/30
CPCC01F11/46C01F5/20C01F5/30C01P2006/80
Inventor 肖林波田承涛徐思红方超李攀红周玲玲
Owner HUBEI SANNING CHEM
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