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Method for comprehensive using tail gas of rotary kiln and dilute sulfuric acid in procedure of producing white titanium pigment through sulfuric acid method

A technology of titanium dioxide and sulfuric acid method, which is applied in chemical instruments and methods, sulfur compounds, inorganic chemistry, etc., can solve the problems of concentrated sulfuric acid with high viscosity, small crystal shape, and difficult solid-liquid separation, and achieve low concentration cost and high acid concentration. Improved effect

Inactive Publication Date: 2007-10-10
ANHUI ANNADA TITANIUM IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The present invention combines the advantages of the above-mentioned patents CN1042527A and CN1171777C, utilizes the physical and chemical properties of sulfuric acid and ferrous sulfate, improves and innovates the process, and realizes the pre-concentration of dilute sulfuric acid with limited rotary kiln tail gas heat. Decrease and increase of sulfuric acid concentration, decrease of solubility properties, increase of FeSO 4 .7H 2 O and FeSO 4 .4H 2 0 crystallization rate, thereby further improving sulfuric acid concentration; Three, utilize ferrous sulfate to be that the solubility decline is not obvious after sulfuric acid concentration is 60%, promptly the solubility curve of ferrous sulfate in sulfuric acid is an inflection point characteristic when sulfuric acid concentration is 60%, according to The production of titanium dioxide and ordinary calcium superphosphate needs to be prepared with acid concentrations of 60-91%, so that the crystallization of ferrous sulfate monohydrate can be precipitated in the acid mixing process, completely solving the problem of FeSO 4 .H 2 O is precipitated during the concentration process and has a small crystal form. It is prone to scaling or clogging during heat exchange and transportation, and concentrated sulfuric acid has problems such as high viscosity and difficult solid-liquid separation.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Example 1: Use a fan at 240m per hour 3 The flow rate is to pump the 450°C rotary kiln tail gas into the pre-concentration tower, and exchange heat with the dilute sulfuric acid with a concentration of 18% sprayed from the top of the tower at 132Kg per hour. The tail gas outlet temperature is 110°C, and 97Kg of pre-concentrated sulfuric acid with a temperature of 90°C and a concentration of 29% is obtained from the bottom of the tower every hour, and the pre-concentrated sulfuric acid is sent to the heat-preserved dense settling tank, and most of the solid titanium is accumulated in the heat-preserved dense settling tank through sedimentation get recycled. After settling, the temperature of the acid solution is 89.5°C. The acid solution is pumped into a medium-temperature concentration device, and secondly concentrated by its own waste heat to obtain a secondary concentrated acid with a temperature of 45°C and a concentration of 32%. The secondary concentrated sulfuric...

Embodiment 2

[0020] Embodiment 2: step is with embodiment 1. Among them, the flow rate of the fan is 235m per hour 3 , the temperature of the tail gas of the rotary kiln is 410°C, and the concentration of dilute sulfuric acid sprayed down from the top of the tower at 130Kg per hour is 20% for heat exchange. The tail gas outlet temperature is 105°C, and 101Kg of pre-concentrated sulfuric acid with a temperature of 80°C and a concentration of 30% is obtained from the bottom of the tower per hour. The acid liquid after sedimentation is concentrated in a medium-temperature concentration device to obtain a concentrated acid with a temperature of 37°C and a concentration of 33%. Crystallization yielded a concentrated acid with a strength of 36%. Mix with 98% industrial sulfuric acid at a ratio of 39:61 to 60% sulfuric acid in the crystallizer for the production of general calcium.

Embodiment 3

[0021] Embodiment 3: step is the same as embodiment 1. Among them, the fan flow rate is 230m per hour 3 , the temperature of the tail gas of the rotary kiln is 370°C, and the concentration of dilute sulfuric acid sprayed down from the top of the tower at 135Kg per hour is 22% for heat exchange. The tail gas outlet temperature is 100°C, and 109Kg of pre-concentrated sulfuric acid with a temperature of 70°C and a concentration of 31% is obtained from the bottom of the tower per hour. The acid solution after sedimentation enters a medium-temperature concentration device and is concentrated to obtain a concentrated acid with a temperature of 25°C and a concentration of 34%. Vacuum crystallization yielded a concentrated acid with a concentration of 37%. Mix with 98% industrial sulfuric acid at a ratio of 16:84 to 88% sulfuric acid in the crystallizer for acidolysis production of titanium ore.

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Abstract

This invention discloses a method for utilizing rotary kiln tail gas and diluted H2SO4 produced during TiO2 powder production by H2SO4 method. The method comprises: contacting rotary kiln tail gas and diluted H2SO4 for heat exchange, settling the obtain pre-concentrated H2SO4, performing medium-temperature concentration by using its own heat, cooling for crystallization in vacuum, and mixing with 98% concentrated H2SO4 to obtain H2SO4 with the concentration needed for TiO2 powder and calcium superphosphate production. This invention effectively utilizes the heat of rotary kiln tail gas for pre-concentration and medium-temperature concentration of diluted H2SO4, and does not need extra heat source. FeSO4 is further precipitated from concentrated H2SO4, thus can realize effective separation of FeSO4 and H2SO4.

Description

technical field [0001] The invention relates to a processing method for the comprehensive utilization of tail gas of a transfer kiln and dilute sulfuric acid produced by sulfuric acid process titanium dioxide. Background technique [0002] The use of sulfuric acid titanium dioxide has the advantages of sufficient raw material sources and low production costs. However, regardless of whether titanium concentrate or high-titanium slag is used as raw material, 6-10 tons of dilute sulfuric acid of about 18-22% is required for each ton of titanium dioxide produced. At present, the dilute sulfuric acid is usually utilized by means of concentration. Since dilute sulfuric acid contains a large amount of FeSO 4 , Ti(SO 4 ) 2 、Al 2 (SO 4 ) 3 and other metal sulfates bring difficulties to utilization. [0003] Patent CN1202989C uses hot flue gas and dilute sulfuric acid to directly contact in a spray tower to concentrate through heat exchange, separate the precipitate, then cool ...

Claims

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Application Information

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IPC IPC(8): C01B17/88
Inventor 叶丽君杨文斌鲁军罗自力
Owner ANHUI ANNADA TITANIUM IND CO LTD
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