High-temperature-resistant cement hexavalent chromium reducing agent

A technology of hexavalent chromium and high temperature resistance, which is applied in the field of building materials, and can solve the problems of affecting the setting time and strength of cement, being difficult to be oxidized, and using a large amount of reducing agent.

Pending Publication Date: 2021-03-09
唐山冀东水泥外加剂有限责任公司 +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the amount of reducing agent is still relatively large, this is because a part of the ferrous salt will be oxidized by the oxygen in the air during the heating process, in order to make up for this part of the consumption and need to add more ferrous salt, the second is because in the heating process The increase in the content of ferric and tetravalent tin ions generated in the reduction of hexavalent chromium will increase the oxidation potential of ferrous and stannous, making ferrous and stannous more difficult to be oxidized than at the beginning. At this time, only by increasing ferrous Iron and stannous content to improve the reduction performance of hexavalent chromium
The increase in the amount of reducing agent will not only increase the cost, but also sometimes affect the setting time and strength of cement

Method used

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  • High-temperature-resistant cement hexavalent chromium reducing agent
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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] 2 parts of stannous sulfate, 20 parts of ferrous sulfate, 3 parts of montmorillonite, 4 parts of bentonite, 3 parts of magnesium fluoride, 5 parts of humic acid.

[0029] Prepare as follows:

[0030] (a) Dissolve 8 parts of ferrous sulfate in water of equal weight and stir evenly, then add montmorillonite, evaporate free water under reduced pressure at room temperature, then dry at 105°C for 2 hours in a nitrogen atmosphere to obtain baked Making montmorillonite;

[0031] (b) Mix and grind the baked montmorillonite, the remaining ferrous sulfate, stannous sulfate, bentonite, magnesium fluoride, and humic acid to 300 mesh, and pack it for later use.

[0032] Mix conventional 42.5 grade cement raw materials to form cement batch, mix and grind the cement batch with the hexavalent chromium reducing agent prepared in this example, and prepare cement according to the 42.5 grade cement preparation process (during 150-160 ℃ high temperature). Among them, 150 grams of hexaval...

Embodiment 2

[0034] 4 parts of stannous sulfate, 25 parts of ferrous sulfate, 5 parts of montmorillonite, 2 parts of bentonite, 5 parts of magnesium fluoride, 3 parts of humic acid.

[0035] Prepare as follows:

[0036] (a) Dissolve 10 parts of ferrous sulfate in water of equal weight and stir evenly, then add montmorillonite, evaporate free water under reduced pressure at room temperature, and then dry at 110°C for 1 hour in a nitrogen atmosphere to obtain baked Making montmorillonite;

[0037] (b) Mix and grind the baked montmorillonite, the remaining ferrous sulfate, stannous sulfate, bentonite, magnesium fluoride, and humic acid to 500 mesh, and pack it for later use.

[0038] Mix conventional 42.5 grade cement raw materials to form cement batch, mix and grind the cement batch with the hexavalent chromium reducing agent prepared in this example, and prepare cement according to the 42.5 grade cement preparation process (during 150-160 ℃ high temperature). Among them, 150 grams of hex...

Embodiment 3

[0040] 3 parts of stannous sulfate, 22 parts of ferrous sulfate, 4 parts of montmorillonite, 3 parts of bentonite, 4 parts of magnesium fluoride, 4 parts of humic acid.

[0041] Prepare as follows:

[0042] (a) Dissolve 9 parts of ferrous sulfate in water of equal weight and stir evenly, then add montmorillonite, evaporate free water under reduced pressure at room temperature, then dry at 107°C for 1.5 hours in a nitrogen atmosphere to obtain baked Making montmorillonite;

[0043] (b) Mix and grind the baked montmorillonite, the remaining ferrous sulfate, stannous sulfate, bentonite, magnesium fluoride, and humic acid to 400 mesh, and pack it for later use.

[0044] Mix conventional 42.5 grade cement raw materials to form cement batch, mix and grind the cement batch with the hexavalent chromium reducing agent prepared in this example, and prepare cement according to the 42.5 grade cement preparation process (during 150-160 ℃ high temperature). Among them, 150 grams of hexav...

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PUM

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Abstract

The invention discloses a high-temperature-resistant cement hexavalent chromium reducing agent, which is prepared from the following components in parts by weight: 2-4 parts of stannous sulfate, 20-25parts of ferrous sulfate, 3-5 parts of montmorillonite, 2-4 parts of bentonite, 3-5 parts of magnesium fluoride and 3-5 parts of humic acid. The reducing agent has stronger high temperature resistance, and hexavalent chromium in cement can be more effectively reduced, so that the using amount of the reducing agent is relatively less, the cost is lower, and the cement performance is good.

Description

technical field [0001] The invention relates to a building material, in particular to a high temperature-resistant cement hexavalent chromium reducing agent. Background technique [0002] Hexavalent chromium is a toxic ion contained in cement. Due to the low-priced chromium ions in the process equipment or raw materials for cement production, they will become hexavalent chromium ions under the high-temperature oxidation conditions in the cement kiln, and finally mixed into the cement. Hexavalent chromium has a corrosive effect on human skin, can cause skin ulceration, and can cause cancer after being mixed into groundwater and finally transferred to the human body. EU law limits the soluble hexavalent chromium in cement to be less than 2ppm (mg / kg), and the Chinese national standard stipulates that the content of soluble hexavalent chromium in cement is not more than 10ppm (mg / kg), while the hexavalent chromium in general cement clinker or cement The content is 5-20ppm. In ...

Claims

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Application Information

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IPC IPC(8): C04B7/60C04B7/42
CPCC04B7/60C04B7/42
Inventor 任建波张露瑶王倩毛泽南张业明
Owner 唐山冀东水泥外加剂有限责任公司
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