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Molten liquid phase roasting method of chromite

A technology of chromite and molten liquid, which is applied in the field of molten liquid phase roasting of chromite, which can solve the problems of high alkali ratio, high production cost, and many free alkalis.

Active Publication Date: 2014-03-19
SICHUAN YINHE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] Chinese patent application publication CN101066779A adopts the hot-mixing calcium-free sodium chromate preparation process, and obtains sodium chromate alkaline liquid through processes such as calcination, hot mixing, slaking, sorting, crushing and leaching. Problems with low wall and chrome ore conversion
Chinese patent application CN98100556.X uses sodium hydroxide molten salt medium to decompose chromite to prepare sodium chromate, and the product is leached in a high alkalinity area. Although this method reduces the reaction temperature, the method has a high alkali ratio and the resulting chromic acid There are many free alkalis in the sodium alkaline solution, the content of impurities is high, the post-treatment process is complicated, and the separation time of impurities is as long as tens of hours. Therefore, the production cost of this method is high and the industrialization is difficult.
As the free space of the kiln is filled with knobs, the charge and flue gas cannot pass through, causing the kiln to stop production

Method used

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  • Molten liquid phase roasting method of chromite
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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0070] ① According to the molar ratio of chromite (calculated as dichromium oxide): soda ash: sodium bicarbonate = 1: 0.8: 4, prepare powdered raw meal, mix evenly, extrude and granulate to obtain granular raw meal;

[0071] ②Put the granular raw meal into the cylindrical horizontal rotary kiln through the feeding port 18a-18b, start the burner, control the reaction temperature to 1150°C, and keep it at this temperature for 30 minutes;

[0072] ③ Then, continuously inject air into the horizontal rotary kiln through oxygen lances 17a-17c, and react at 1150°C for 2 hours, during which the reaction mixture is in a molten liquid phase; and

[0073] ④The gas generated in the horizontal rotary kiln is removed from the flue gas outlet, and the liquid phase clinker is removed through the high-level liquid phase outlet, leached with water, and filtered to obtain sodium chromate alkaline liquid and iron slag. The measured chrome ore conversion rate (that is, the percentage of chromium i...

Embodiment 2

[0075] ① According to the molar ratio of chromite (calculated as dichromium trioxide): soda ash: sodium chromate=1: 2: 1.2, prepare powdered raw meal, mix evenly, extrude and granulate to obtain granular raw meal;

[0076] ②Put the granular raw meal into the cylindrical horizontal rotary kiln through the feeding port 18a-18b, start the burner, control the reaction temperature to 950°C, and keep it at this temperature for 30 minutes;

[0077] ③ Then, continuously spray oxygen-enriched air with an oxygen volume concentration of 65% into the horizontal rotary kiln through oxygen lances 17a-17c, and react at 950°C for 4.5h, during which the reaction mixture is in a molten liquid phase; and

[0078] ④The gas generated in the horizontal rotary kiln is removed from the flue gas outlet, and the liquid phase clinker is removed through the high-level liquid phase outlet, leached with water, and filtered to obtain sodium chromate alkaline liquid and iron slag. It is determined that the c...

Embodiment 3

[0080] ① According to the molar ratio of chromite (in terms of chromium trioxide): soda ash: sodium hydroxide = 1: 8: 0.5, prepare powdered raw meal, mix evenly, extrude and granulate to obtain granular raw meal;

[0081] ②Put the granular raw meal into the cylindrical horizontal rotary kiln through the feeding port 18a-18b, start the burner, control the reaction temperature to 520°C, and keep it at this temperature for 40 minutes;

[0082] ③ Then, continuously spray oxygen-enriched air with an oxygen volume concentration of 65% into the horizontal rotary kiln through oxygen lances 17a-17c, and react at 520°C for 0.8h, during which the reaction mixture is in a molten liquid phase; and

[0083] ④ The gas generated in the horizontal rotary kiln is removed from the flue gas outlet, and the molten liquid phase clinker is removed through the high-level liquid phase outlet, leached with water, and filtered to obtain sodium chromate alkaline liquid and iron slag. It is determined tha...

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Abstract

The invention relates to a molten liquid phase roasting method of chromite. The molten liquid phase roasting method comprises the following step of: performing molten liquid phase roasting on a mixture comprising chromite and optional sodium chromate in a horizontal rotary kiln in the presence of oxygen at 350-1,500 DEG C to obtain sodium chromate, wherein the mixture also comprises one or more of soda, sodium bicarbonate, sodium sulfate and sodium hydroxide; the horizontal rotary kiln comprises a kiln body and two end parts at the two ends of the kiln body; the two end parts are provided with a high-position liquid phase outlet and a low-position liquid phase outlet respectively; the kiln body is provided with an oxygen lance and a feed port; the oxygen lance and the feed port are arranged in a stagger way so as not to be on the same cross section of the kiln body; and a smoke outlet which is positioned on the kiln body is arranged between the high-position liquid phase outlet and one of the feed port and the oxygen lance closer to the high-position liquid phase outlet. According to the method, the chromite is in molten liquid phase in a molten salt system, so that the chromium conversion rate is greatly increased, the yield is increased, and the problem of high probability of wall attachment of a calcium-free roasting process is substantially solved.

Description

technical field [0001] The invention relates to a molten liquid phase roasting method of chromite. Background technique [0002] As a basic chemical raw material, sodium red alum occupies an important position in the national economy and is widely used in chemical industry, light industry, metallurgy, printing and dyeing, machinery, daily hardware and other industries. The raw material of sodium rufite mainly comes from sodium chromate produced by roasting chromite ore. The roasting process of chromite is mainly divided into calcium roasting and calcium-free roasting. Their basic principles are to oxidize and roast chromite ore and soda ash under high temperature conditions to convert the chromium in the ore into water-soluble sodium chromate. [0003] Calcium roasting has a large amount of slag discharge, and the Cr in the slag 6+ The content is high, and it contains the carcinogen calcium chromate, which seriously pollutes the environment. Calcium-free roasting uses se...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22B1/02C22B34/32
Inventor 李先荣陈宁王方兵
Owner SICHUAN YINHE CHEM
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