A detoxification method for chromium slag dry fixation detoxification

A technology of chromium slag and dry method, which is applied in the field of remediation and disposal of hazardous solid waste containing heavy metals, can solve the problems of chromium slag detoxification treatment process research difficulties, little long-term stability process research and development, and low stable solidification efficiency, and achieve industrialization prospects Optimistic, good heat fixation effect, good stabilization effect

Active Publication Date: 2015-08-19
GUANGDONG INST OF ECO ENVIRONMENT & SOIL SCI
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Problems solved by technology

[0005] However, in general, the detoxification treatment process of chromium slag has always been a difficult research point, especially for the long-term stability process after chromium slag treatment.
The currently reported stable curing technology has the disadvantages of low stable curing efficiency and short stable time. Under certain conditions, such as high temperature or rain washing, chromium may be re-oxidized or volatilized or leached out. Chromium exposed to the air has May be re-oxidized to toxic Cr(VI), presenting high environmental risk

Method used

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  • A detoxification method for chromium slag dry fixation detoxification
  • A detoxification method for chromium slag dry fixation detoxification
  • A detoxification method for chromium slag dry fixation detoxification

Examples

Experimental program
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Effect test

Embodiment 1

[0027] Example 1: The thermal fixation and detoxification process of iron-based reduction fixative (a mixture of zero-valent iron and ferric oxide) on chromium trioxide and evaluation of its curing effect.

[0028] The process flow of chromium trioxide fixation and detoxification based on iron-based reduction fixative of this embodiment includes the following steps:

[0029] (1) Combining zero-valent iron, Fe 2 O 3 And Cr 2 O 3 Mix in different ratios of 20:20:60, 20:25:55 and 25:25:50 in molar ratios;

[0030] (2) Rotate and mix the samples with different molar ratios in a mixer for 2 hours;

[0031] (3) The fully mixed sample is compressed into a cylindrical compact with a height of 2cm in diameter at a pressure of ≥200Bar in the tablet press;

[0032] (4) Put the compacted cylindrical compacted bodies into a high-temperature furnace for sintering. The cylindrical bodies of each ratio are calcined at 1200°C for 4 hours. After calcining, the solidified and detoxified sintered body of c...

Embodiment 2

[0035] Example 2: Iron-based reduction fixative (a mixture of zero-valent iron and ferric oxide, the ratio of the amount of the substance is 1:1) to evaluate the thermal fixation and detoxification process of chromium slag and its curing effect.

[0036] In this example, the chromium slag was collected from the chromium slag piled pit in the chromium salt workshop of a chemical plant in South China. The plant had ceased production in the 1980s. The chromium slag was piled in the pit without any treatment and was stored in the chromium slag. The waste rock pit was sealed with 20cm thick cement until now.

[0037] The chromium slag fixation and detoxification process flow based on iron-based reduction fixative of this embodiment includes the following steps:

[0038] (1) After the chromium slag is collected, it is air-dried and ground to a particle size of 1~2mm;

[0039] (2) Mix the iron-based reducing agent and the chromium slag in different ratios of 10:90, 20:80 and 30:70 by mass;

...

Embodiment 3

[0045] Example 3: The thermal fixation and detoxification process of chromium slag with iron-based reduction fixative (ferrous oxalate) and the evaluation of its curing effect.

[0046] In this example, the chromium slag was collected from the chromium slag piled pit in the chromium salt workshop of a chemical plant in South China. The plant had ceased production in the 1980s. The chromium slag was piled in the pit without any treatment and was stored in the chromium slag. The waste rock pit was sealed with 20cm thick cement until now.

[0047] The chromium slag fixation and detoxification process flow based on iron-based reduction fixative of this embodiment includes the following steps:

[0048] (1) After the chromium slag is collected, it is air-dried and ground to a particle size of 1~2mm;

[0049] (2) Mix ferrous oxalate and chromium slag in different mass ratios of 10:90, 20:80, 30:70, 40:60;

[0050] (3) Rotate and mix samples with different mass ratios in a mixer for 2 hours;

...

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Abstract

The invention discloses a detoxifying method for fixing detoxification through adopting chromium slag dry method. The detoxifying method comprises the steps of evenly mixing a mixture of zero-valent iron and ferric oxide with Cr2O3 according to the substance ratio of more than or equal to 40:60, or with the chromium slag according to the mass ratio of more than or equal to 10:90, and compacting, wherein the quantity ratio of zero-valent iron to ferric oxide is 1:1-1.25; or, evenly mixing ferrous oxalate with chromium slag according to the mass ratio of more than or equal to 10:90 and then compacting under the pressure of more than or equal to 200Bar, and calcinating compaction bodies into sintered bodies at 900-1200 DEG C in anaerobic atmosphere, thus realizing the detoxification fixing through the chromium slag dry method. By using the technique, an iron-based reducing fixing agent and the chromium slag are mixed, compacted and calcinated, chromium exists in the compact bodies in a low-toxic trivalent chromium manner, the chromium is fixed by the compaction bodies in a vitrification melting manner and is fixed in the compact bodies in a spinel crystal structure manner, and the stabilizing effect is good; in addition, iron exists in the same crystal structure in a reducing-state Fe(II) manner, the chromium can be prevented from being oxidized to be toxic due to long-time environment exposure, and the properties of the spinel structure body is stable, therefore, no secondary pollution can be generated.

Description

Technical field: [0001] The invention belongs to the technical field of repair and disposal of hazardous solid waste containing heavy metals, and specifically relates to a detoxification method for chromium slag. Background technique: [0002] Chromium slag is the residue after adding soda ash, dolomite, and limestone to chromite, roasting at a high temperature of 1100-1200℃, and leaching sodium chromate with water. In the traditional chromium salt production enterprises and a few metal chromium enterprises in the sodium dichromate production process, a large amount of chromium slag is usually produced. Under normal circumstances, the production of 1 ton of metallic chromium produces about 10 tons of chromium slag; the production of 1 ton of chromium salt produces 3 to 5 tons of chromium slag. Since the first chromium salt production line was built in my country in 1958, more than 70 enterprises have produced chromium salt. Most of these enterprises are small in scale and backw...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B09B3/00B09B5/00
Inventor 刘承帅廖长忠施凯闵李芳柏陶亮
Owner GUANGDONG INST OF ECO ENVIRONMENT & SOIL SCI
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