Device and method for producing type II anhydrous gypsum from phosphogypsum

Anhydrous gypsum, phosphogypsum technology, applied in chemical instruments and methods, inorganic chemistry, calcium/strontium/barium sulfate, etc., can solve the problems of high raw material cost, impact on performance, large product fluctuation, etc. The effect of resource utilization, stable performance and stable quality

Pending Publication Date: 2020-02-18
JIANGSU EFFUL SCIENCE AND TECHNOLOGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] CN 109553372A discloses a method for preparing and using a recyclable phosphogypsum roadbed material. Phosphogypsum with a free moisture content of 7-20% is added to a saturated calcium hydroxide solution for neutralization reaction to obtain soluble phosphate radical removal Phosphogypsum with fluoride ions, and then calcined at a high temperature of 170-350 ° C to convert the dihydrate gypsum into Type III anhydrous gypsum, and mix the prepared Type III anhydrous gypsum with water, water reducing agent and waterproofing agent mixed to obtain the phosphogypsum roadbed material, but the anhydrous gypsum prepared by this method is easy to hydrate, and water reducer and waterproofing agent still need to be added, the cost of raw materials is relatively high, and insoluble impurities are not removed during the impurity removal process, affect its performance
[0005] CN 105985036A discloses a processing method of phosphogypsum. After mixing phosphogypsum and lime, it is added

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  • Device and method for producing type II anhydrous gypsum from phosphogypsum

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Embodiment 1

[0089] This embodiment provides a device for producing type II anhydrite from phosphogypsum, the structural connection schematic diagram of the device is as follows figure 1 As shown, it includes a pretreatment unit 2, a drying unit 3, a calcining unit 4 and a product collection unit 8 connected in sequence, the pretreatment unit 2 includes a spiral stirring device 21, and the drying unit 3 includes a breaking device 31 and at least one A drying device, the calcining unit 4 includes a calcining device 42, and a heat source pipeline is arranged in the calcining device 42.

[0090] The helical stirring device 21 comprises a double-helical stirrer, the double-helical stirrer is provided with a stirring paddle, and the stirring paddle is an internal hollow structure; the upper part of the spiral stirring device 21 is provided with a moisture outlet, and the lower part is also provided with a There is a supplementary air port; the pretreatment unit 2 also includes a first induced d...

Embodiment 2

[0100] This embodiment provides a device for producing type II anhydrite from phosphogypsum. The structure of the device refers to the structure in embodiment 1, the difference is that the drying device of the drying unit 3 includes two stages, two stages of drying The solid outlet of the device 33 is connected to the calcining unit 4; the calcining device 42 is inclined downward from the inlet to the outlet, with a gradient of 1.5%.

Embodiment 3

[0106] This embodiment provides a method for producing Type II anhydrite from phosphogypsum, said method is carried out using the device in Example 1, comprising the following steps:

[0107] (1) react after mixing phosphogypsum and calcium oxide, the content of free hydrogen ion in the phosphogypsum satisfies the pH value of 3, the content of soluble phosphate is 1.4wt%, the content of soluble fluorine is 0.75wt%, and the content of free water accounts for 20wt% of the total amount of phosphogypsum, the grade of phosphogypsum is 92%, the mass ratio of said phosphogypsum to calcium oxide is 17500:1, and the temperature of said reaction is 60°C;

[0108] (2) Dispersing and drying the product obtained in step (1), the average particle size of the raw material after disintegration is 35 μm, the number of drying stages is 4, and the temperature of the next stage of drying is higher than that of the previous stage of drying The temperature of dispersing and drying at different leve...

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Abstract

The invention provides a device and a method for producing type II anhydrous gypsum from phosphogypsum. The device comprises a pretreatment unit, a drying unit, a calcining unit and a product collecting unit which are sequentially connected, wherein the pretreatment unit comprises a spiral stirring device; the drying unit comprises a scattering device and at least one-stage drying device; the calcining unit comprises a calcining device; and a heat source pipeline is arranged in the calcining device. According to the device disclosed by the invention, the phosphogypsum is accurately converted into the II-type anhydrous gypsum through the combination of pretreatment, drying and calcination processes, soluble phosphorus and fluorine in the phosphogypsum are effectively removed, conversion ofinsoluble phosphorus and decomposition of organic matters are realized, the problem of acid corrosion is solved, and the influence of harmful impurities on gypsum products is reduced; the method improves the comprehensive utilization efficiency of the phosphogypsum, the product is not easy to hydrate, the product can be compounded with super sulfate cement, supersulphated cement or gypsum composite cementing materials, the product has stable performance and high strength, and the application way of the phosphogypsum is expanded.

Description

technical field [0001] The invention belongs to the technical field of solid waste utilization, and relates to a device and method for producing Type II anhydrite from phosphogypsum. Background technique [0002] Phosphoric acid is an important industrial product. Its production is mainly based on sulfuric acid wet process. The by-product of this method is mainly phosphogypsum. Every ton of phosphoric acid produced produces about 7 tons of phosphogypsum containing about 20% of free water. The output of the product is huge, which not only takes up a lot of storage space, but also brings serious pollution to the surrounding environment. Therefore, the recovery and resource utilization of phosphogypsum is essential. However, due to the main and side reactions between phosphate rock and sulfuric acid and the additives added in the beneficiation process, the types of impurities in the by-product phosphogypsum are complex and the concentration range is wide, which will seriously a...

Claims

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Application Information

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IPC IPC(8): C04B11/028C04B11/26C01F11/46
CPCC04B11/028C04B11/26C04B11/266C01F11/466
Inventor 宋小霞万建东彭卓飞唐永波唐绍林陈家伟刘丽娟
Owner JIANGSU EFFUL SCIENCE AND TECHNOLOGY CO LTD
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