阅读说明：本技术 一种磷石膏增白方法 (Ardealite whitening method ) 是由 李山山 唐永波 于 2020-07-15 设计创作，主要内容包括：本发明公开了一种磷石膏增白方法,包括煅烧、酸浸、洗涤,本发明以磷石膏为原料,利用该方法能将原料20左右白度磷石膏提高到白度大于90,大大的提高了磷石膏白度,可以解决由于白度低在一些方面的应用受到限制的问题,进而提高了磷石膏的附加值；本发明的煅烧助剂可以与金属杂质进行反应生成水洗和酸洗可以去除的化合物,避免了直接煅烧生成的难溶性的金属氧化物,而造成磷石膏白度提高不显著的弊端。(The invention discloses a phosphogypsum whitening method, which comprises the steps of calcining, acid leaching and washing, wherein phosphogypsum is used as a raw material, the whiteness of the phosphogypsum of about 20 percent of the raw material can be improved to be more than 90 by utilizing the method, the whiteness of the phosphogypsum is greatly improved, the problem that the application of the phosphogypsum is limited in some aspects due to low whiteness can be solved, and the additional value of the phosphogypsum is further improved; the calcining auxiliary agent can react with metal impurities to generate a compound which can be removed by washing and pickling, and the defect that the whiteness of the phosphogypsum is not remarkably improved due to the fact that insoluble metal oxides are generated by direct calcining is overcome.)

1. The phosphogypsum whitening method is characterized by comprising the following steps:

s1, calcining: placing the phosphogypsum and the calcining auxiliary agent into a heating container for calcining, and taking out for later use after cooling to obtain a calcined material; the calcination auxiliary agent is one of ammonium acetate, ammonium carbonate, ammonium phosphate, ammonium bicarbonate, sodium chloride, EDTA disodium and thiourea dioxide;

s2, acid leaching: drying the calcined material calcined in the step S1, and mixing the dried calcined material with water to form a suspension; putting the suspension into a reaction vessel, adding a sulfuric acid solution into the reaction vessel, putting the reaction vessel into a constant-temperature water bath kettle, and stirring for reaction;

s3, washing: and (5) after the reaction in the step S2 is finished, cooling the reaction liquid, performing suction filtration, washing until the filtrate is neutral, drying, and whitening.

2. The phosphogypsum whitening method according to claim 1, characterized in that the mass ratio of the phosphogypsum to the calcining auxiliary agent in the step S1 is 0.0005-0.06: 1.

3. the phosphogypsum whitening method according to claim 1, characterized in that in the step S1, the calcining temperature of the phosphogypsum and the calcining auxiliary agent is 500-700 ℃; the calcination time is 1-3 h.

4. The phosphogypsum whitening method according to claim 1, characterized in that in the step S2, the mass ratio of the calcined material to the water is 1: 4-8.

5. The phosphogypsum whitening method according to claim 1, characterized in that in the step S2, the mass ratio of the suspension to the sulfuric acid solution is 1: 8-1: 20; the concentration of the sulfuric acid solution is 1-2 mol/L.

6. The phosphogypsum whitening method according to claim 1, characterized in that in the step S2, the temperature in the constant temperature water bath is 50-100 ℃.

7. The phosphogypsum whitening method according to claim 1, characterized in that in the step S3, the filtrate is washed until the filtrate is neutral and then dried at 45 ℃.

Technical Field

The invention relates to a phosphogypsum whitening method.

Background

Phosphogypsum is a solid waste discharged in the production of wet-process phosphoric acid. At present, the accumulated stacking quantity of phosphogypsum in China exceeds 2.5 hundred million tons, and the annual emission quantity reaches 7000 million tons. Because the phosphogypsum has high impurity content and complex components, such as undecomposed phosphorite, phosphoric acid, calcium fluoride, iron, aluminum compounds, organic matters and other impurities, the whiteness of the phosphogypsum is low, and the phosphogypsum is generally light yellow, light grey or grey black, the phosphogypsum can only be used for cement industry, chemical raw materials, soil conditioners, roadbeds or industrial fillers and the like, and although the utilization ways of the phosphogypsum are more, the resource utilization rate is always low and the added value is not high. If the phosphogypsum is subjected to impurity removal and purification to prepare the white gypsum, the utilization value of the phosphogypsum can be greatly improved, the natural white gypsum with high price and scarcity can be replaced, and the consumption of mineral resources and the damage to the ecology are reduced.

Patent CN102923752A describes a technical method for whitening phosphogypsum, but the method has no effect and is not significant for gypsum with lower whiteness, and the whiteness of the whitened gypsum is not significantly improved.

Disclosure of Invention

Aiming at the defects of the prior art, the invention solves the problems that: provides a phosphogypsum whitening method with good whitening effect.

In order to solve the problems, the technical scheme adopted by the invention is as follows:

a method for whitening phosphogypsum, which comprises the following steps:

s1, calcining: placing the phosphogypsum and the calcining auxiliary agent into a heating container for calcining, and taking out for later use after cooling to obtain a calcined material; the calcination auxiliary agent is one of ammonium acetate, ammonium carbonate, ammonium phosphate, ammonium bicarbonate, sodium chloride, EDTA disodium and thiourea dioxide;

s2, acid leaching: drying the calcined material calcined in the step S1, and mixing the dried calcined material with water to form a suspension; putting the suspension into a reaction vessel, adding a sulfuric acid solution into the reaction vessel, putting the reaction vessel into a constant-temperature water bath kettle, and stirring for reaction;

s3, washing: and (5) after the reaction in the step S2 is finished, cooling the reaction liquid, performing suction filtration, washing until the filtrate is neutral, drying, and whitening.

Further, the mass ratio of the phosphogypsum to the calcining auxiliary agent in the step S1 is 0.0005-0.06: 1.

further, in the step S1, the calcining temperature of the phosphogypsum and the calcining auxiliary agent is 500-700 ℃; the calcination time is 1-3 h.

Further, in the step S2, the mass ratio of the calcined material to the water is 1: 4-8.

Further, in the step S2, the mass ratio of the suspension to the sulfuric acid solution is 1: 8-1: 20; the concentration of the sulfuric acid solution is 1-2 mol/L.

Further, in the step S2, the temperature in the constant temperature water bath is 50 to 100 ℃.

Further, in the step S3, the filtrate is washed until the filtrate is neutral, and then dried at 45 ℃.

The invention has the advantages of

The invention provides a phosphogypsum whitening method, which takes phosphogypsum as a raw material, can improve the whiteness of the phosphogypsum to more than 90 by using the method, greatly improves the whiteness of the phosphogypsum, can solve the problem that the application of the phosphogypsum is limited in some aspects due to low whiteness, and further improves the additional value of the phosphogypsum; the calcining auxiliary agent can react with metal impurities to generate a compound which can be removed by washing and pickling, and the defect that the whiteness of the phosphogypsum is not remarkably improved due to the fact that insoluble metal oxides are generated by direct calcining is overcome.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.