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Technique for preparing sodium pyrophosphate from wet method phosphoric acid

A technology of sodium pyrophosphate and preparation process, which is applied in phosphorus compounds, chemical instruments and methods, inorganic chemistry, etc., can solve the problems of high energy consumption, high price, and large pollution of yellow phosphorus, so as to control impurity content and ensure product quality. , the effect of low impurity content

Inactive Publication Date: 2009-08-19
SICHUAN HONGDA
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But its disadvantage is that thermal phosphoric acid is prepared from yellow phosphorus. Due to the high energy consumption and high price of yellow phosphorus, the price is more than 10,000 yuan / ton, so the product cost is extremely high, not only the manufacturer's profit is low, and the production enthusiasm is lacking. Moreover, downstream product manufacturers are unwilling to use a large amount of sodium hexametaphosphate, which greatly limits the application range of sodium hexametaphosphate. So far, there are few downstream products of sodium hexametaphosphate, and the price is high, which cannot meet the growing market demand.
[0004] In addition, due to the high energy consumption and heavy pollution in the preparation of yellow phosphorus, which does not comply with current industrial and environmental protection policies, many yellow phosphorus factories have been closed, and the source of raw materials is difficult.

Method used

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  • Technique for preparing sodium pyrophosphate from wet method phosphoric acid
  • Technique for preparing sodium pyrophosphate from wet method phosphoric acid
  • Technique for preparing sodium pyrophosphate from wet method phosphoric acid

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Embodiment 1

[0032] see figure 1 , the steps of this process are:

[0033] 1. Add sulfuric acid to phosphate rock powder, filter after stirring, and remove slag to obtain wet-process phosphoric acid. The P of this phosphoric acid is 2 o 5 The best concentration is ≥18%, so phosphate rock with a higher grade should be selected to increase the yield of the product.

[0034] 2. Add 1000kg 18% P 2 o 5 The wet-process phosphoric acid is placed in the neutralization tank, and 109kg of sodium hydroxide with a concentration of 98% is added to neutralize the reaction with phosphoric acid. The reaction temperature is controlled at 90°C and the reaction time is 50 minutes to prepare a slurry containing sodium dihydrogen phosphate. The reaction formula as follows

[0035] h 3 PO 4 +NaOH==NaH 2 PO 4 +H 2 o

[0036] The slurry is a mixed slurry, which contains a lot of impurities, mainly SO 2 2- , Fe 2 o 3 、Al 2 o 3 , MgO and other solid phases.

[0037] 3. Filter the slurry, collect t...

Embodiment 2

[0049] Difference with embodiment one is only, in the 2nd step, replaces sodium hydroxide with 133kg 98% sodium carbonate, reacts with phosphoric acid, and reaction formula is as follows

[0050] 2H 3 PO 4 +NaCO 3 =2NaH 2 PO 4 +H 2 O+CO 2 ↑

[0051] All the other are the same as the first embodiment.

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Abstract

The invention discloses a process for preparing sodium pyrophosphate using wet-process phosphoric acid as a raw material. c. filter the slurry obtained in step b above, and collect the clear liquid; d. add ammonia to the clear liquid and react with it to obtain a compound containing e. cooling and concentrating the slurry to crystallize the compound therein; f. filtering the concentrated slurry to collect the compound crystal; g. heating the compound crystal to volatilize the NH3 in it to obtain Crystallization of sodium dihydrogen phosphate; h. Reaction of crystallization of sodium dihydrogen phosphate with sodium hydroxide to obtain disodium hydrogen phosphate; i. Polymerization of disodium hydrogen phosphate to obtain sodium pyrophosphate. The advantages of this process are: low comprehensive energy consumption and low production cost.

Description

technical field [0001] The invention relates to a preparation process of sodium pyrophosphate, in particular to a process for preparing sodium pyrophosphate using wet-process phosphoric acid as a raw material. Background technique [0002] Sodium pyrophosphate is an important chemical raw material, which is widely used in water treatment, oil drilling, mineral processing and chemical fiber. In recent years, the market demand has been increasing day by day. [0003] The traditional process of preparing sodium pyrophosphate at home and abroad uses thermal phosphoric acid as raw material. The steps are: first neutralize thermal phosphoric acid and sodium hydroxide to obtain sodium dihydrogen phosphate, and then mix sodium dihydrogen phosphate with sodium hydroxide Neutralize again to obtain disodium phosphate, and finally polymerize disodium phosphate to obtain the target product sodium pyrophosphate. The advantages of this process are that there are few impurities in the reac...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/42
Inventor 张凌陈维贵马功富刘庆发张勇
Owner SICHUAN HONGDA