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Method for recovering chromium from iron and steel plant waste water and sludge, and its resource utilization method

A technology for recycling wastewater sludge and chromium, applied in the field of solid waste treatment and recycling, can solve the problems of high recovery cost, acid consumption, insufficient chromium content, etc. easy effect

Active Publication Date: 2006-07-26
徐州美利圆环保科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although these technologies have temporarily disposed or utilized chromium-containing sludge, trivalent chromium in sludge products is still a considerable hidden danger, and chromium resources in sludge have not been recycled.
The invention patent application with application number 200410060869.1 discloses a method for preparing iron oxide black and iron red pigments from steelmaking converter sludge, but this technology does not involve the recovery of chromium
If the chromium-containing sludge is directly used as a raw material for the production of chromium salts, there are also a series of problems: the chromium content is not high enough, the existing chromium salt production technology produces a large amount of slag, and it is not feasible to convert a waste residue into a larger waste residue
The main difficulties in the implementation of this method are: the pH value of the filtrate needs to be adjusted to 1.5 during the extraction process, thus consuming a large amount of acid; the separation effect of chromium, iron, and zinc during the extraction process is not ideal, and the organic solution cannot be reused
There is also research on mixing potassium carbonate and potassium hydroxide with sludge and then burning to recover chromium, but the addition of potassium hydroxide makes the recovery cost too high. When used to treat the above sludge, the pH value of the leaching process solution is too high Dissolves zinc and makes chromium salts difficult to purify

Method used

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  • Method for recovering chromium from iron and steel plant waste water and sludge, and its resource utilization method

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0029] The composition of a batch of wastewater sludge from a steel company in Shanghai is shown in Table 1:

[0030] elements and ingredients

[0031] The "non-volatile other solid impurities" listed in Table 1 refer to SiO 2 , CaSO 4 And Mn, Mg compounds. "Volatile solid impurities" refer to the weight loss when calcined above 600°C. Mix the sludge (calculated on a dry basis, the same below) with sodium carbonate at a mass ratio of 1:0.6, dry the sludge in a rotary kiln heater to a granular form, grind it finely, and roast it at 700°C for 4 hours. The high-temperature flue gas generated during the roasting process can be used as a heat source for sludge drying. Then add pure water at the ratio of solid-to-liquid mass ratio of 1:5 to leach chromium from the roasted product for 2 consecutive times, each leaching time is 0.5h, and add extremely dilute NaOH at the ratio of solid-to-liquid mass ratio of 1:2.5 for the third time Solution leaching, and supplemented by...

example 2

[0033] The composition of a batch of wastewater sludge from a steel company in Shanghai is shown in Table 2:

[0034] elements and ingredients

[0035] The sludge and sodium carbonate were mixed in a mass ratio of 1:0.8, and the sludge was dried to granular form in the rotary kiln heater (due to CaSO 4 The dried sludge is naturally granulated), ground into fine powder, and roasted at 800°C for 2 hours. The high-temperature flue gas generated during the roasting process can be used as a heat source for sludge drying. Then add pure water in the ratio of solid-liquid mass ratio 1:10 to extract chromium from the roasted product at 50°C. During the extraction process, air is introduced for 1h. Finally, the natural pH=11.95, and the concentration of chromium in the leaching solution is 8.97g / L, while the concentrations of iron and zinc were around 180ug / L and 200ug / L, respectively. The recovery rate of chromium is more than 80%. After adding structural aids and pore-for...

example 3

[0037] The iron and steel mill sludge in Example 1 was mixed with potassium carbonate at a mass ratio of 1:0.6, and the sludge was dried in a rotary kiln heater to a granular form, then ground, and then calcined at 900° C. for 1 hour. The high-temperature flue gas generated during the roasting process can be used as a heat source for sludge drying. Then add pure water at a solid-liquid ratio of 1:10 to extract chromium from the roasted product at 120°C. The extraction time is 2 hours, the natural pH=12.01, and the concentration of chromium in the extract is about 9.2g / L, while iron and zinc The concentrations are around 100ug / L and 120ug / L respectively. Then add a very dilute KOH solution with a solid-to-liquid mass ratio of 1:8, and leaching with air for 10 hours. The concentration of chromium in the leaching solution is about 1.87g / L, while the concentrations of iron and zinc are both below 100ug / L. The recovery rate of chromium is over 90%. After adding structural aids an...

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Abstract

The invention relates to a method to recover the Cr element and make proper use to the residue in sewage and sludge from steel plant. Wherein, drying the sludge to mix with Na2CO3 or K2CO3 by ratio as 1: 0. 4~1 and roast for 0. 5~6h at 600-900Deg; leaching with water by ratio as 1: 5~10 for 0. 2~12h to recover Cr element; and adding necessary auxiliary agent to prepare biogas desulfurizer with the separated residue as well material. The whole process produces no pollutent.

Description

technical field [0001] The invention relates to a method for recovering chromium in the wastewater sludge of a steel plant and making the residue suitable for resource utilization, and belongs to the technical field of solid waste treatment and resource utilization. Background technique [0002] The sludge produced after wastewater treatment in steel plants contains 10-13% chromium, more than 12% iron and 1-8% zinc. This sludge is equivalent to the chromium content of low-grade chromite ore, and has considerable chromium recovery value. However, chromium mainly exists in the trivalent state, which is difficult to separate from iron and zinc. In the prior art, for the treatment of chromium-containing sludge, there are building materials (invention patent application number: 01105197) or building material additives (invention patent application number: 87105027.7). Although these technologies have temporarily disposed or utilized chromium-containing sludge, trivalent chromiu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F11/06C02F11/12C02F101/22C02F103/16
Inventor 陈德珍徐科袁园
Owner 徐州美利圆环保科技有限公司
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