Method for detoxifying chromium slag by using high sulfur coal

Patent metadata

Field	Value
Publication number	US-11478672-B2
Application number	US-202016809685-A
Country	US
Kind code	B2
Filing date	Mar 5, 2020
Priority date	Mar 6, 2019
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

The present invention discloses a method for detoxifying chromium slag by using high sulfur coal. The method includes: sieving chromium slag into coarse-grained chromium slag and fine-grained chromium slag, air-drying and crushing both the coarse-grained chromium slag and the fine-grained chromium slag; separately mixing the crushed coarse-grained chromium slag and fine-grained chromium slag with the crushed high sulfur coal uniformly; adjusting pH values of a coarse-grained slag mixture and a fine-grained slag mixture to 8.0-11.0 and moisture content thereof to 12%-18%; conducting reduction on the treated coarse-grained slag mixture and fine-grained slag mixture, where the reduction temperature of the fine-grained slag mixture is 500-700° C., the reduction time of the fine-grained slag mixture is 10-30 min, the reduction temperature of the coarse-grained slag mixture is 800-1000° C., the reduction time of the coarse-grained slag mixture is 10-30 min; after the reduction, conducting water quenching, and discharging the product.

First claim

What is claimed is:

1. A method for detoxifying chromium slag by using high sulfur coal, specifically comprising the following steps:
(1) sieving chromium slag into coarse-grained chromium slag and fine-grained chromium slag, wherein a grain size of the coarse-grained chromium slag is greater than or equal to 10 meshes, and a grain size of the fine-grained chromium slag is less than 10 meshes; air-drying and crushing both the coarse-grained chromium slag and the fine-grained chromium slag; and air-drying and crushing high sulfur coal;
(2) separately mixing the crushed coarse-grained chromium slag and fine-grained chromium slag in step (1) with the high sulfur coal uniformly, to obtain a coarse-grained slag mixture and a fine-grained slag mixture;
(3) adjusting pH values of the coarse-grained slag mixture and the fine-grained slag mixture in step (2) to 8.0-11.0 and moisture content thereof to 12%-18% by spraying water or an acid solution;
(4) separately conducting stirring and reduction on the treated coarse-grained slag mixture and fine-grained slag mixture in step (3) in a rotary kiln, wherein the reduction temperature of the fine-grained slag mixture is 500-700° C., the reduction time of the fine-grained slag mixture is 10-30 min, the reduction temperature of the coarse-grained slag mixture is 800-1000° C., and the reduction time of the coarse-grained slag mixture is 10-30 min; and
(5) mixing reduced coarse-grained slag mixture and fine-grained slag mixture in step (4), conducting water quenching for cooling the slag mixture to below 300° C., and discharging the product.

2. The method for detoxifying chromium slag by using high sulfur coal according to claim 1 , wherein the coarse-grained chromium slag, the fine-grained chromium slag, and the high sulfur coal in step (1) are air-dried at normal temperature for more than 24 h, and the coarse-grained chromium slag, the fine-grained chromium slag, and the high sulfur coal are all crushed until they can pass through a sieve of 20 meshes.

3. The method for detoxifying chromium slag by using high sulfur coal according to claim 1 , wherein in step (2), the mass fractions of chromium slag in the coarse-grained slag mixture and the fine-grained slag mixture are 85%-95%, and the mass fraction of high sulfur coal is 5%-15%.

4. The method for detoxifying chromium slag by using high sulfur coal according to claim 1 , wherein the acid solution in step (3) is a dilute H 2 SO 4 solution or a FeSO 4 solution.

5. The method for detoxifying chromium slag by using high sulfur coal according to claim 1 , wherein the rotary kiln in step (4) is internally provided with a helical stirring device; the helical stirring device comprises a helical blade ( 1 ) and a rotary rod ( 2 ); the rotary rod ( 2 ) traverses the rotary kiln; and the helical blade ( 1 ) is arranged on the rotary rod ( 2 ).

6. The method for detoxifying chromium slag by using high sulfur coal according to claim 1 , wherein a solvent for the water quenching in step (5) is water or a FeSO 4 solution, and the mass fraction of the FeSO 4 solution is 1%-5%.

Assignees

• Univ Kunming Science & Technology

Inventors

• Ning Ping
• Li Bin
• He Liwei
• Lin Zhang
• Liu Xueming

Classifications

• A62D3/37

  by reduction, e.g. hydrogenation · CPC title

• C22B34/32 Primary

  Obtaining chromium · CPC title

• A62D2101/40

  Inorganic substances · CPC title

• A62D2101/24

  containing heavy metals · CPC title

• A62D2203/02

  Combined processes involving two or more distinct steps covered by groups A62D3/10 - A62D3/40 · CPC title