Cement hexavalent chromium compounded reducing agent and preparation method thereof

A hexavalent chromium and composite type technology, which is applied in the field of cement hexavalent chromium composite reducing agent and its preparation, can solve the problems of easy loss of reducibility, etc., achieve strong reducing ability, reduce costs, and improve early strength and later strength Effect

Active Publication Date: 2017-02-01
NANJING YONGNENG MATERIALS
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Cement is generally alkaline, and many reducing agents can only play a reducing role under acidic conditions, and it is easy to lose their reducing properties under alkaline conditions. There

Method used

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  • Cement hexavalent chromium compounded reducing agent and preparation method thereof

Examples

Experimental program
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Effect test

Example Embodiment

[0019] Example 1: A cement hexavalent chromium composite reducing agent, the composition is as follows:

[0020] Sodium sulfite 15%, ferrous sulfate 70%, manganese sulfate 10%, stannous sulfate (tin (II)) 5%, the total amount is 100%; the percentages are all mass percentages.

[0021] The preparation method of cement hexavalent chromium composite reducing agent, the steps are: first disperse and mix sodium sulfite, manganese sulfate, and stannous sulfate according to the formula ratio, stir slowly in a mixer for 30 seconds to obtain the mixture; then divide the ferrous sulfate into more Add to the mixture in one time: first add 20% ferrous sulfate and stir slowly for 120s; then add 20% ferrous sulfate and stir slowly for 120s; after the addition is complete, stir slowly for more than 5 minutes until the mixture is uniform; After the impurities are filtered through the mesh stainless steel sieve, product 1 is obtained.

Example

[0022] Example 2 to Example 5:

[0023] Repeat the method of Experimental Example 1 according to the content of each component specified in Table 1 below to obtain cement hexavalent chromium composite reducing agent products 2 to 5 with different component content:

[0024] Table 1

[0025] Composition (%) Example 1 Example 2 Example 3 Example 4 Example 5 Sulfite1517182015 Ferrous sulfate7065616068 Manganese sulfate1012201510 Stannous sulfate561510 get Product 1 Product 2 Product 3 Product 4 Product 5

[0026] The hexavalent chromium composite reducing agent product 1 to product 5 obtained in the examples were tested separately in a Φ500×500 standard test mill. The specific process is as follows:

[0027] Mix according to the following material ratio: 63% by mass clinker, 8% by mass, 18% by mass slag, 11% by mass fly ash, and then 0.005% trioxide Chromium to obtain a mixture material.

[0028] The hexavalent chromium composite reducing agent product obtained in the embodiment...

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Abstract

The invention discloses a cement hexavalent chromium compounded reducing agent. The reducing agent comprises, by mass, 15-20% of sodium sulfite, 60-70% of ferrous sulfate, 10-20% of manganese sulfate and 1-10% of stannous sulfate, and the sum of mass percentages of all above components is 100%. The cement hexavalent chromium compounded reducing agent has good chemical stability and can reduce water-soluble hexavalent chromium into trivalent chromium, the content of hexavalent chromium keeps 2 ppm for three months, the reducing agent can reduce the fineness of cement before the cement is milled, and also can substantially increase the 3 d strength and the 28 d strength of the cement, and the actual amount of the reducing agent is less than 1/10 of the use amount of ferrous sulfate. The reducing agent has the characteristics of high reduction rate, good selectivity, simplicity in experiment operation, cheap and easily available raw materials and very high application prospect.

Description

technical field [0001] The invention relates to a cement hexavalent chromium composite reducing agent and a preparation method thereof. Background technique [0002] In 1950, it was discovered in Europe that the soluble chromium compounds in Portland cement can cause serious adverse symptoms to the human body, which is called cement dermatitis. Masons and concrete workers have been exposed to soluble hexavalent chromium in cement for a long time, and the above symptoms will be manifested. The series of descriptions of strong carcinogenicity, DNA breakage, and genotoxicity all point to the same environmental heavy metal pollutant—hexavalent chromium. At present, in the production process of Portland cement clinker, chromium is one of the unavoidable trace elements in raw materials. Usually the chromium content of Portland cement is between 100ppm and 300ppm. Oxidation and alkaline conditions in cement kilns will promote the formation of hexavalent chromium, and the applica...

Claims

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Application Information

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IPC IPC(8): C04B7/42
CPCC04B7/425
Inventor 刘国华李晓静
Owner NANJING YONGNENG MATERIALS
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