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Process for enhanced reduction bleaching of kaolin by using thiocarbamide

A technology of kaolin and kaolin ore, applied in aluminum silicate, silicate and other directions, can solve problems such as equipment corrosion, environmental pollution, and difficulty in calcining whiteness to reach 90%, and achieve the effect of improving whiteness and high brightness

Active Publication Date: 2010-07-14
广西兖河矿业有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above methods have a certain effect on improving the whiteness, but the range of improvement is limited, and the calcined whiteness is difficult to reach more than 90%.
In foreign countries, nascent liquid dithionite plus borohydride is used for enhanced reduction bleaching. Although the product whiteness can be close to 90%, the reducing agent borohydride is expensive and difficult to be practically applied in industry, and the yellowing of kaolin after bleaching The phenomenon is difficult to control, that is, the iron in the solution is easy to return to the clay minerals; the existing sodium hydrochloride reduction bleaching method, the bleaching reaction is carried out under strong acid conditions, which seriously corrodes the equipment, causes great environmental pollution, and has limited bleaching effect

Method used

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  • Process for enhanced reduction bleaching of kaolin by using thiocarbamide
  • Process for enhanced reduction bleaching of kaolin by using thiocarbamide

Examples

Experimental program
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Effect test

Embodiment 1

[0015] Beihai kaolin belongs to incompletely weathered granite weathering residual deposits. Impurities such as iron-bearing minerals such as iron-bearing mica and iron oxide ore in raw ore have affected the wide application of Beihai kaolin. In this embodiment, the raw material of North Sea kaolin is selected, the natural whiteness is about 77%, the calcined whiteness is about 82%, and the calcined temperature is 1200° C. (the same below). First, add 600kg of kaolin to water and stir to make slurry, add dispersant sodium hexametaphosphate and sodium hydroxide pH adjuster with 0.2% kaolin weight, the pH value of the slurry is about 7.0-8.5, and the stirring time is 30 minutes, and it is adjusted to 23-28 % mud, then carry out sedimentation purification, sedimentation to a mud volume concentration of about 20%, then adjust the pH value of the slurry to 3.0 with sulfuric acid, then add 0.6% of kaolin weight sodium dithionite and 0.2% kaolin weight of auxiliary reducing agent thio...

Embodiment 2

[0017] In the bleaching reaction, the consumption of the auxiliary reducing agent thiourea is changed to 0.5% of the kaolin weight, other conditions are the same as in Example 1, and the kaolin concentrate product with a natural whiteness of 86.2% is obtained, and its whiteness is 91.3% after calcining. %.

Embodiment 3

[0019] In the bleaching reaction, when other conditions are the same as in Example 1, without adding the auxiliary reducing agent thiourea, the obtained kaolin concentrate product has a natural whiteness of 80% and a calcined whiteness of 83.4%. It shows that the bleaching effect is not obvious.

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Abstract

The invention relates to a process for enhanced reduction bleaching of kaolin by using thiocarbamide, which uses sodium dithionite as a main reducing agent and the thiocarbamide as an auxiliary reducing agent to perform combined enhanced bleaching on the kaolin under a Zn / gamma-Al2O3 catalyzed condition with the pH value of 3.0 to 6.5 at the normal temperature, and simultaneously perform a shielding reaction and a complex reaction. The process solves the problem that the kaolin is yellowed after bleaching, and has the characteristics of low cost, good bleaching effect and small environmental pollution; besides, a kaolin powder product has the natural whiteness of over 85 percent and the calcination whiteness of over 90 percent, has high brightness, stability and dispersity, and can be widely used in the industries of high-grade fine ceramics, coatings, papermaking and the like.

Description

technical field [0001] The invention relates to a production process for bleaching kaolin, in particular to a thiourea-enhanced reduction bleaching process for kaolin, which is widely applicable to the bleaching of clay minerals. Background technique [0002] Kaolin is an inorganic non-metallic mineral raw material, which is mainly composed of kaolinite, mica, residual feldspar and quartz. It is easy to disperse and suspend in water, and has unique properties such as good plasticity, high cohesiveness and ion exchange capacity, so it is widely used It is used in important industrial fields such as ceramics, paper making, chemical industry and medicine. Pure kaolin is white, but kaolin in nature is often associated with some dark minerals such as hematite, magnetite goethite and iron-containing mica; in addition, kaolin itself also absorbs some coloring substances, and part of it participates in kaolin Structural iron (replacing aluminum in the three-octahedron) is formed in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/26
Inventor 邓元臣李晓鸣夏光华陈强朱永杰苏小丽
Owner 广西兖河矿业有限公司
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