Method for production of phosphoric acid and combined production of a-hemihydrate gypsum through dehydrate-hemihydrate wet phosphoric acid technology

A technology of phosphogypsum dihydrate and phosphogypsum hemihydrate, which is applied in the field of phosphoric acid, can solve problems such as low phosphorus recovery rate, low phosphoric acid concentration, and difficult utilization of dihydrate phosphogypsum, so as to save energy, increase phosphoric acid concentration, and solve the problem of phosphorus The effect of excessive content

Active Publication Date: 2013-05-08
WENGFU (GRP) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to solve the problems of low phosphoric acid concentration, low phosphorus recovery rate and difficult utilization of dihydrate phosphogypsum produced by the dihydrate phosphoric acid process, and to provide a dihydrate-semi-water wet-process phosphoric acid process for co-production of a-half Phosphogypsum method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Example 1: Weigh 2380g of phosphate concentrate slurry, add 7600g of 24% dilute phosphoric acid, heat up to 70°C, add H 2 SO 4 (98%) 1376g, liquid-solid ratio 2.5:1, react for 1.5h and then filter, part of the filtrate is used as finished phosphoric acid, its concentration is 35%P 2 o 5 , part of which is used to prepare back acid. The filter cake enters the next step of reaction, add 6000g of 20% dilute phosphoric acid, heat up to 94°C, add H 2 SO 4 (98%) 900g, liquid-solid ratio 2.5:1, reacted for 2h and then filtered, the filter cake was washed with 3000g hot water, filtered phosphoric acid and washing liquid were used to prepare back acid, the filter cake was analyzed as a-phosphogypsum hemihydrate , containing 5% crystal water, free P in gypsum 2 o 5 The mass percentage is 0.4%.

Embodiment 2

[0018] Example 2: Weigh 2400g of phosphate concentrate powder, add 7600g of 24% dilute phosphoric acid, heat up to 75°C, add H 2 SO 4 (98%) 1376g, liquid-solid ratio 2.5:1, reacted for 2.5h, then filtered, a part of the filtrate was used as finished phosphoric acid, and its concentration was 37%P 2 o 5 , part of which is used to prepare back acid. The filter cake enters the next step of reaction, add 6000g of 20% dilute phosphoric acid, heat up to 90°C, add H 2 SO 4 (98%) 950g, liquid-solid ratio 2.5:1, reacted for 1.5h, then filtered, the filter cake was washed with 3100g hot water, filtered phosphoric acid and washing liquid were used to prepare back acid, the filter cake was analyzed as a-semi-water Phosphogypsum, containing 5.8% crystal water, free P in gypsum 2 o 5 The mass percentage of is 0.36%.

Embodiment 3

[0019] Example 3: Weigh 2500g of phosphate concentrate powder, add 7800g of 24% dilute phosphoric acid, heat up to 80°C, add H 2 SO 4 (98%) 1380g, liquid-solid ratio 2.5:1, react for 3.0h and then filter, part of the filtrate is used as finished phosphoric acid, its concentration is 39%P 2 o 5 , part of which is used to prepare back acid. The filter cake enters the next step of reaction, add 6100g of 20% dilute phosphoric acid, heat up to 86°C, add H 2 SO 4 (98%) 950g, liquid-solid ratio 2.5:1, reacted for 1.0h, then filtered, the filter cake was washed with 3200g hot water, filtered phosphoric acid and washing liquid were used to prepare back acid, the filter cake was analyzed as a-semi-water Phosphogypsum, containing 7% crystal water, free P in gypsum 2 o 5 The mass percentage of 0.2%.

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Abstract

The invention discloses a method for the production of phosphoric acid and the combined production of a-hemihydrate gypsum through a dehydrate-hemihydrate wet phosphoric acid technology. A dehydrate part production technology is characterized in that the reaction tank temperature is 70-80DEG C, the retention time is 1.5-3h, the free sulfate radical concentration is 1-2%, and the produced wet phosphoric acid concentration omega(P2O5) is 35-39%. A hemihydrate part production technology is characterized in that the reaction tank temperature is 86-94DEG C, the retention time is 1-2h, and the mass concentration of free sulfate radicals is 6-8%. Phosphoric acid produced through the hemihydrate technology has a concentration omega(P2O5) of 10-15% and is used as a recycle acid of the dehydrate part, the crystal water content of the combined-production hemihydrate gypsum is 5-7%, the mass percentage of free P2O5 in gypsum is less than 0.4%, and the crystal form of the produced hemihydrate gypsum is a-hemihydrate gypsum. Compared with the dehydrate technology, the method disclosed in the invention improves the phosphoric acid concentration and improves the phosphorus recovery rate to above 98%, and the combined-production a-hemihydrate gypsum can be directly used as a building gypsum product, so energy consumption saving is realized.

Description

technical field [0001] The invention relates to phosphoric acid, in particular to a method for producing phosphoric acid and co-producing a-hemihydrate phosphogypsum by a dihydrate-semihydrate wet-process phosphoric acid process. Background technique [0002] The industrial production methods of phosphoric acid can be divided into two categories, one is thermal production, and the obtained product is called thermal phosphoric acid, and the industrial element phosphorus is oxidized and absorbed to produce phosphoric acid. Elemental phosphorus is generally produced by electric furnace method, so it is also called electrothermal phosphoric acid. [0003] The other is wet-process production, and the product is called wet-process phosphoric acid. In a broad sense, phosphoric acid produced by decomposing phosphate rock with strong inorganic acids (such as sulfuric acid, hydrochloric acid, nitric acid, fluosilicic acid, etc.) can be collectively referred to as wet-process phosphor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/231C01F11/46
Inventor 胡宏解田薛绍秀刘旭杨丽萍
Owner WENGFU (GRP) CO LTD
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