Method for reducing content of magnesium in feed grade calcium hydrophosphate

A technology for the content of calcium hydrogen phosphate and magnesium, which is applied in the field of phosphate, can solve the problems of reducing the content of calcium hydrogen phosphate and magnesium in feed grade, the high cost of nitric acid or nitrate, and the relatively large impact of equipment corrosion, so as to reduce production costs and simplify the process Effective and stable operation effect

Active Publication Date: 2014-04-16
WENGFU (GRP) CO LTD
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Problems solved by technology

If the phosphate rock contains higher magnesium, the phosphoric acid produced from the phosphate rock will contain higher magnesium, and magnesium will precipitate out into the product during the main neutralization process of preparing calcium hydrogen phosphate, and a large amount of magnesium will enter the feed Grade calcium hydrogen phosphate will cause the calcium index in the product to fail to meet the requirements of GB / T 22549-2008
[0004] Chinese patent 200610022563.6 is titled "A method for preparing fine calcium phosphate salt by using phosphogypsum return water / or partial washing liquid of phosphogypsum", and Chinese patent 201110292726.3 is titled "A kind of preparation of feed grade calcium hydrogen phosphate by phosphate fertilizer factory wastewater method", these two patents disclose the method of preparing feed grade calcium hydrogen phosphate by using phosphogypsum backwater, phosphate fertilizer factory wastewater and the like phosphorus chemical industry phosphorus wastewater after purification, but because phosphorus chemical industry phosphorus wastewater often contains a large amount of These magnesium ions will also precipitate out into the product during the neutralization process of preparing calcium hydrogen phosphate. When a large amount of magnesium enters the feed grade calcium hydrogen phosphate, the calcium index in the product will not meet the GB / T 22549- 2008 requirements
[0005] Chinese patent 02133810.8 is entitled "Method for preparing calcium hydrogen phosphate from high-magnesium phosphate rock", and Chinese patent 99114617.4 is entitled "Method for reducing magnesium and extracting calcium in the production of calcium hydrogen phosphate for feed". Calcium soluble acid is added during the extraction process or soluble calcium salt or calcium soluble inorganic acid is added during the main neutralization process to achieve the purpose of reducing the magnesium content in feed grade calcium hydrogen phosphate, but this patented method introduces impurities into the production system Ions such as chloride ions and nitrate ions, these ions will be enriched and circulated in the system, affecting production, and chloride ions have a greater impact on equipment corrosion, and the cost of using nitric acid or nitrate is also higher

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  • Method for reducing content of magnesium in feed grade calcium hydrophosphate

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Embodiment 1

[0019] Take 1t of purification solution (P 2 o 5 is 7%, MgO is 1.1%), add milk of lime and neutralize at 50°C for 1.5h, the pH value at the end of the neutralization reaction is 6.3, at this time, the solid phase in the reaction slurry is about 175kg on a dry basis, of which MgO is about 3.8 %, add 10kg of 98% sulfuric acid and react at 50°C for 25 minutes. The amount of sulfuric acid added is about 0.6 times the stoichiometric ratio of the magnesium content in the solid phase of the slurry at the end of the neutralization reaction. After the reaction, the pH value of the slurry at the end point is 5.2. The slurry after the reaction is centrifuged, and the obtained feed grade calcium hydrogen phosphate product 164kg after the filter cake is dried contains P 2 o 5 39.3%, Ca21.2%, MgO1.9%; the separated liquid phase is neutralized with milk of lime to a pH value of 10, and then filtered, and the filtrate is returned to the phosphoric acid system to prepare milk of lime for rec...

Embodiment 2

[0021] Phosphorus-extracting chemical industry phosphorus-containing wastewater 1t (P 2 o 5 is 6.0%, MgO is 0.62%), adding lime milk and sodium sulfide to defluorinate and remove impurities to obtain a purified solution of about 980kg (P 2 o 5 is 4.6%, MgO is 0.58%), add lime milk and react at 45°C for 1.3h, the pH value at the end of the neutralization reaction is 6.2, at this time, the solid phase in the reaction slurry is about 114kg on a dry basis, of which MgO is about 3.5 %, add 5kg of 98% sulfuric acid and react at 45°C for 30 minutes. The amount of sulfuric acid added is about 0.5 times the stoichiometric ratio of the magnesium content in the solid phase of the slurry at the end of the neutralization reaction. After the reaction, the pH value of the slurry at the end point is 5.5. The slurry after the reaction is centrifuged, and the obtained feed grade calcium hydrogen phosphate product 108kg after the filter cake is dried contains P 2 o 5 39.1%, Ca20.7%, MgO2.0%;...

Embodiment 3

[0023] Phosphorus-extracting chemical industry phosphorus-containing wastewater 1t (P 2 o 5 is 1.6%, MgO is 0.20%), adding lime milk and sodium sulfide to defluorinate and remove impurities to obtain a purified solution of about 990kg (P 2 o 5 1.3% and MgO 0.19%), add milk of lime and neutralize at 40°C for 2 hours, and the pH value at the end of the neutralization reaction is 6.8. At this time, the solid phase in the reaction slurry is about 32kg on a dry basis, of which MgO is about 5.0% , add 7kg of 98% sulfuric acid and react at 35°C for 40 minutes. The amount of sulfuric acid added is about 1.3 times the stoichiometric ratio of the magnesium content in the solid phase of the slurry at the end of the neutralization reaction. After the reaction, the pH value of the slurry at the end is 4.4. The slurry after the reaction is centrifuged, and the obtained feed grade calcium hydrogen phosphate product is 28kg after the filter cake is dried, which contains P 2 o 5 38.7%, Ca2...

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Abstract

A method for reducing content of magnesium in feed grade calcium hydrophosphate is characterized in that a purified liquid obtained after defluorination and purification of phosphoric acid by a wet process with sulfuric acid or phosphorus wastewater of the phosphorus chemical industry is subjected to neutralization reaction with lime cream, sulfuric acid is added after reaction to reduce the content of magnesium in a reaction slurry solid phase, the adding amount of sulfuric acid is 0.5-1.3 times of stoichiometric ratio of the magnesium content in a reaction endpoint slurry solid phase, slurry is filtered after the reaction, and a feed grade calcium hydrophosphate product is obtained after a filter cake is dried; and a separated liquid phase is added into the lime cream, neutralized to the pH value of 8-10 and then filtered, and filtrate is recycled. The method can effectively reduce the content of magnesium in feed grade calcium hydrophosphate, the calcium content can be improved, and the method has the characteristics of simple and effective process, easiness in reaction operation and good economic benefit.

Description

technical field [0001] The invention relates to phosphate, in particular to a method for reducing magnesium content in feed grade calcium hydrogen phosphate. Background technique [0002] Feed grade calcium hydrogen phosphate (CaHPO 4 2H 2 O, referred to as feeding calcium) is a poultry and livestock feed additive rich in phosphorus and calcium. The phosphorus and calcium participate in the metabolism of the animal body, form hormones, enzymes and vitamins, and maintain a certain amount of nutrients in the animal bones. The proportion of phosphorus and calcium can prevent animals from various diseases caused by phosphorus and calcium deficiency. Feed grade calcium hydrogen phosphate is the most commonly used product in feed phosphate, and is recognized as one of the best feed mineral additives at home and abroad. [0003] Feed-grade calcium hydrogen phosphate is widely used in the production process of traditional wet-process phosphoric acid to produce feed-grade calcium ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/32
Inventor 刘旭何浩明解田胡宏石玲元龙庆兰
Owner WENGFU (GRP) CO LTD
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