Method for detoxifying and curing Cr(VI) by using FeCl2.6H2O added metakaolin based geopolymer

A technology of fecl2·6h2o and mineral polymers, applied in the field of Cr(Ⅵ) pollution control, can solve problems such as difficulty in inhibiting acid-soluble Cr leaching, and achieve good durability, good impermeability, and high curing rate.

Active Publication Date: 2012-07-25
中部知光技术转移有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

However, the materials involved in the solidification method in the prior art are mainly cement and mineral polymers, and the limitations of cement itself make it difficult to inhibit the leaching of acid-soluble Cr(VI)
However, there is no effective method for curing Cr(VI) with mineral polymers.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] A method that utilizes the addition of FeCl 2 ·6H 2 O metakaolin-based mineral polymer detoxification and solidification Cr (Ⅵ) method, it comprises the following steps:

[0023] 1) Add 5g of solid NaOH to 25g of water glass solution to form an alkaline activator solution; then add 30g of metakaolin to the above alkaline activator solution in stages, stir and mix evenly to obtain a mixed solution;

[0024] 2) Then add 0.042g K in turn 2 Cr 2 o 7 and 0.6g FeCl 2 ·6H 2 O to the mixed solution obtained in step 1), and mix well;

[0025] 3) The solution obtained in step 2) was poured into a mold of 20×20×20 mm, cured at 60°C, demoulded, sealed with a polyethylene film, and cured at 60°C for 1 hour to obtain a mineral polymer with Cr immobilized.

[0026] According to the U.S. EPA-TCLP method, the leaching concentration of total chromium is measured. The specific method is: the above-mentioned obtained Cr-fixed mineral polymer is pulverized to less than 9mm, and the l...

Embodiment 2

[0033] A method that utilizes the addition of FeCl 2 ·6H 2 O metakaolin-based mineral polymer detoxification and solidification Cr (Ⅵ) method, it comprises the following steps:

[0034] 1) Add 5g of solid NaOH to 25g of water glass solution to form an alkaline activator solution; then add 30g of metakaolin to the above alkaline activator solution in stages, stir and mix evenly to obtain a mixed solution;

[0035] 2) Then add 0.170g K in turn 2 Cr 2 o 7 and 0.78g FeCl 2 ·6H 2 O to the mixed solution obtained in step 1) and mix well;

[0036] 3) The solution obtained in step 2) was poured into a mold of 20×20×20 mm, cured at 60°C, demoulded, sealed with a polyethylene film, and cured at 60°C for 1 hour to obtain a mineral polymer with Cr immobilized.

[0037] The leaching concentration of total chromium obtained in Example 2 is 1.44 mg / L, and the solidification rate of chromium is 99.73%, which meets the Cr(VI) treatment requirements of the US EPA-TCLP law.

Embodiment 3

[0039] A method that utilizes the addition of FeCl 2 ·6H 2 O metakaolin-based mineral polymer detoxification and solidification Cr (Ⅵ) method, it comprises the following steps:

[0040] 1) Add 5g of solid NaOH to 25g of water glass solution to form an alkaline activator solution; then add 30g of metakaolin to the above alkaline activator solution in stages, stir and mix evenly to obtain a mixed solution;

[0041] 2) Then add 0.170g K in turn 2 Cr 2 o 7 and 0.9g FeCl 2 ·6H 2 O to the mixed solution obtained in step 1) and mix well;

[0042] 3) The solution obtained in step 2) was poured into a mold of 20×20×20 mm, cured at 60°C, demoulded, sealed with a polyethylene film, and cured at 60°C for 1 hour to obtain a mineral polymer with Cr immobilized.

[0043] The leaching concentration of total chromium obtained in Example 3 is 0.11mg / L, and the solidification rate of chromium is 99.98%, which meets the treatment requirements of Cr(VI) in the US EPA-TCLP method.

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PUM

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Abstract

The invention provides a method for detoxifying and curing Cr(VI) by using FeCl2.6H2O added metakaolin based geopolymer, comprising the following steps of: (1) adding metakaolin to an alkali activator solution gradually, stirring uniformly to obtain a mixed solution; (2) adding Cr(VI) and FeCl2.6H2O sequentially to the mixed solution obtained in the step (1) and mixing uniformly, wherein the addition of the Cr(VI) is less than or equal to 0.8% by mass of the mixed solution obtained in the step (1), the addition of the FeCl2.6H2O is less than or equal to 12% by mass of the mixed solution obtained in the step (1), and the mass ratio of the FeCl2.6H2O to the Cr(VI) is greater than or equal to 13; and (3) sequentially molding, curing, demolding and aging the solution obtained in the step (2) to obtain the Cr fixed geopolymer. The method provided by the invention has a high chromium curing rate and is environment-friendly and suitable for controlling acid soluble Cr.

Description

technical field [0001] The invention belongs to the pollution control method of Cr(Ⅵ), in particular to a 2 ·6H 2 O. Metakaolin-based mineral polymers for detoxification and solidification of Cr(VI). Background technique [0002] Chromium salt is an important chemical basic raw material. The production of chromium salt adopts high-temperature roasting-water immersion-multi-stage evaporation crystallization process, the conversion rate of chromium is 75%, and the residue is discharged as chromium slag. About 1.7-4.2 tons of highly toxic chromium slag is discharged for every 1 ton of sodium chromate produced, and about 7 tons of chromium slag is discharged for every 1 ton of metal chromium produced. According to statistics, since the production of chromium salts in the 1950s, more than 20 cities in my country have accumulated 6 million tons of chromium slag stockpiles, and less than 2 million tons have been disposed of. The main chemical components of chromium slag are CaO...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): A62D3/33A62D101/43
Inventor 陈洁渝王焰新王洪权严春杰朱小燕
Owner 中部知光技术转移有限公司
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