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A method for preventing multi-effect concentration and single-effect fouling of titanium white waste acid from sulfuric acid process

A titanium dioxide waste acid, multi-effect concentration technology, applied in sulfur trioxide/sulfuric acid, chemical instruments and methods, sulfur compounds, etc., can solve the problems of high operating cost, high steam volume, low equipment utilization rate, etc. The process is simple and easy to implement, the effect of improving the vacuum degree of the first effect and reducing the consumption of energy

Active Publication Date: 2020-06-23
JINAN YUXING CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that during the concentration process, with the increase of acid concentration, salts, especially calcium salts and ferrous salts, will continue to precipitate, causing serious blockage of equipment and pipelines. In order to ensure normal operation, it is necessary to stop and clean frequently or Mechanical cleaning, and the cycle is getting shorter and shorter. In the end, the driving time is not as long as the parking cleaning time. The equipment utilization rate is low, the operating cost is high, the labor intensity is high, and the operation is very troublesome.
[0006] Although the use of single-effect concentration can solve the problem of fouling and clogging, the mass fraction of waste acid is concentrated to 55--65%, and the concentration unit is good and the steam volume is large. The comprehensive cost is high, which is not acceptable to every titanium dioxide production enterprise.

Method used

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  • A method for preventing multi-effect concentration and single-effect fouling of titanium white waste acid from sulfuric acid process
  • A method for preventing multi-effect concentration and single-effect fouling of titanium white waste acid from sulfuric acid process
  • A method for preventing multi-effect concentration and single-effect fouling of titanium white waste acid from sulfuric acid process

Examples

Experimental program
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Effect test

Embodiment 1

[0028] Preheat the titanium dioxide waste acid with a sulfuric acid concentration of 23% (iron-titanium ratio 0.28) into the first-effect concentration system, add the second-effect concentrate with a concentration of 55%, and keep the sulfuric acid concentration in the first-effect concentration system at 38%. The temperature is 103°C and the vacuum is 52kpa. At this time, a large amount of salt will precipitate and form large particles. The sulfuric acid in the first-effect concentration system overflows into the second-effect concentration system. Keep the temperature of the second-effect concentration system at 76.5°C and the vacuum at 91kpa. Concentrate to a concentration of 53% sulfuric acid, and remove large particles of salt by filtration. The inner wall of the pipeline of the equipment will not produce scale during the continuous production process, and there is no need for maintenance and parking for descaling, which saves time and cost. figure 1 It can be seen that ...

Embodiment 2

[0030] Preheat the titanium dioxide waste acid with a sulfuric acid concentration of 20% (iron-titanium ratio 0.30) and pass it into the first-effect concentration system, add concentrated sulfuric acid with a concentration of 98%, keep the sulfuric acid concentration in the first-effect concentration system at 42%, and the temperature is 106 ℃, the vacuum degree is 52kpa, at this time, a large amount of salt will precipitate and form large particles. The concentration is 55% sulfuric acid, and the large particles of salt are removed by filtration. The inner wall of the pipeline of the equipment will not produce scaling phenomenon, and there is no need for maintenance and descaling, which saves time and cost.

Embodiment 3

[0032]Preheat the titanium dioxide waste acid with a sulfuric acid concentration of 30% (iron-titanium ratio 0.42) and pass it into the first-effect concentration system, add the second-effect concentrate with a concentration of 55%, and keep the sulfuric acid concentration in the first-effect concentration system at 40%. The temperature is 104°C and the vacuum is 50kpa. At this time, a large amount of salt will precipitate and form large particles. The sulfuric acid in the first-effect concentration system overflows into the second-effect concentration system. Keep the temperature of the second-effect concentration system at 77°C and the vacuum at 90kpa. Concentrate to a concentration of 54% sulfuric acid, and remove large particles of salt by filtration. The inner wall of the pipeline of the equipment will not produce scaling phenomenon, and there is no need for maintenance and descaling, which saves time and cost.

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Abstract

The invention discloses a method for preventing one-effect scaling during multi-effect concentration of waste acid of sulfate process titanium dioxide. Waste acid with a concentration of 20-30% (including waste acid generated by pre-concentration of rotary kiln tail gas) produced by a titanium dioxide production workshop is directly introduced into a prehearer and a one-effect heater for heating,wherein the one-effect heater has a temperature of 103-106 DEG C and a vacuum degree of 48-52 KPa; concentrated finished acid or two-effect concentrated acid overflowing into a curing tank are injected into a one-effect concentration system according to a certain ratio of the one-effect concentrated acid, wherein dynamic equilibrium is achieved under the condition that the acid content is stabilized to be 38% or above, and FeSO4.7H2O and CaSO4.2H2O in the waste acid are instantly dehydrated; precipitates of sulfates of Fe ions, Ca ions and the like are precipitated as reduction of solubility,and the process can be regarded as combination of self-seed crystals with in-phase salts for generating solid precipitates, so that the precipitates of sulfates of the Fe ions, Ca ions and the like are prevented from being implanted on low-end and high-end interfaces of the temperature gradient, and formation of calcium sulphate-based layered scale and Fe salt-based bridge plug are avoided.

Description

technical field [0001] The invention relates to the technical field of waste acid treatment produced by sulfuric acid process titanium dioxide production, in particular to a method for preventing multi-effect concentration and single-effect scaling of sulfuric acid process titanium dioxide waste acid. Background technique [0002] Titanium dioxide is widely used in all walks of life and is in great demand. At present, the production of titanium dioxide mainly adopts sulfuric acid method, chlorination method and hydrochloric acid method. In my country, 90% of titanium dioxide is produced by sulfuric acid method. Waste acid will be generated in the production process of titanium dioxide. It takes 1 ton of titanium dioxide to produce Discharge 6-7 tons of waste acid, which contains about 20% of sulfuric acid, ferrous sulfate, calcium sulfate and other salts, insoluble titanium dioxide, soluble titanium, etc., a large number of impurities limit the long-term stability of the conc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F1/04C01B17/88C01B17/90C02F103/34
CPCC01B17/88C01B17/90C02F1/042C02F2103/34C02F2301/063C02F2301/08
Inventor 潘向雷宋代磊杨颖辉吕小军高鬲李达徐梦
Owner JINAN YUXING CHEM