CN1085832A

CN1085832A - Process flow for treating leached-out chromium residue

Info

Publication number: CN1085832A
Application number: CN92107188A
Authority: CN
Inventors: 曾庆琳; 曾旭; 周建云
Original assignee: 曾庆琳
Priority date: 1992-10-17
Filing date: 1992-10-17
Publication date: 1994-04-27

Abstract

It is to adopt " leaching-physical sepn-reduction acidleach " technology that leached-out chromium residue is handled, at first with solubility Cr ^{+ 6}Leach after reduction, neutralizing treatment get Cr (OH) ₃Precipitation, residue chromium slag separates with the magnesia brick refractory materials with the oxide compound of physical method with chromium, iron according to the proportion different mining, thereby at last the oxide compound of chromium, iron is handled through the reduction acidleach oxide compound of iron is reduced to metallic iron, leach with the diluted acid dissolving then, chromated oxide is insoluble to be stayed in the residue.100 tons of chromium slags of every processing can get CrO ₃About 2 tons, about 60 tons in high-quality magnesia brick refractory materials, about 10 tons of higher-grade chromites, the present invention is applicable to that all adopt the producer of chromic salts or chromium metal to promote the use of.

Description

Chromium leaching slag treatment process

The invention provides a process flow for treating chromium leaching slag.

The leached chromium slag is produced in the process of producing chromium salt or metal chromium from chromite, and is produced through the processes of leaching calcined clinker of chromite, soda, dolomite and other reaction material with water, filtering, producing chromate from filtrate, and obtaining leached chromium slag with 1-1.5% water soluble CrO residue₃And 1-1.2% acid soluble CrO₃15-17% of the chromium in the raw ore is lost with the slag. At present, there are two ways for treating chromium slag: comprehensive utilization: (1) replacing dolomite as a filling material; (2) the iron ore is replaced to be used as a glass colorant to produce a emerald green glass bottle; (3) replacing chromite as a crystallization promoter to manufacture the glauconite cast stone; (4) replacing serpentine as a solvent to manufacture the calcium magnesium phosphate fertilizer; (5) production of chromium slag cast stone, and reagent C₆Shaped synthetic ammonia conversion catalystCoal, chromium-barium slag bricks, artificial spicules and the like, and the methods are high in cost and cannot realize industrial application. (II) non-toxic treatment: there are a coal powder reduction roasting method, a cyclone furnace treatment method in a power plant and a sodium sulfide reduction method, and the above methods cause secondary pollution and have high treatment cost, so that the problem of utilization of chromium slag is not solved. At present, the amount of discharged chromium slag is 11-12 ten thousand tons every year in China, except for dispersed disposal, the amount of chromium slag piled up in the whole country is more than 150 ten thousand tons, which not only occupies a large amount of land, but also fine grains fly with wind to cause air pollution, dust and air containing chromium compounds are inhaled by a human body to cause nasal mucosa congestion, erosion, serious ulcer, perforation of nasal septum, headache, dizziness, cough, spitting and other systemic poisoning symptoms, and hexavalent chromium can be directly carcinogenic. In rainy days, the water-soluble chromate flows into rivers, lakes and seas along with rainwater, and pollutes surface water andunderground water sources. Furthermore, the method is simple. The chromium slag with the greatest harm is soluble chromic acid slag which is a strong oxidant and has high toxicity and is easy to be poisoned by long-term contact, so that the effective utilization of the chromium leaching slag is a problem to be solved urgently.

The invention aims to provide a treatment process flow which has large economic benefit, small investment and large slag treatment amount and can be industrialized, the process flow can well solve the problem of treatment of the pending chromium leaching slag for a long time, the waste is really changed into valuable, and the currently abandoned and useless or even harmful chromium leaching slag is treated into useful substances.

The key point of the invention is that a 'leaching-physical separation-reduction acid leaching' process is adopted, and soluble hexavalent chromium (CrO) exists in chromium slag₃) Therefore, firstly, we must leach out the chromium slag to contain Cr⁺⁶The solution (2) is subjected to reduction, neutralization, filtration and the like to obtain Cr (OH)₃After precipitation, comprehensive utilization is carried out; simultaneously, the other components which are not dissolved in water after being leached are separated from the oxides of other components by a physical method according to different specific gravities, and the proportion of the ferrochrome is adjusted to be more than three through reduction acid leaching, thereby obtaining high-grade chromite, and the rest slag of the chromiteThe high-quality magnesia brick refractory material mainly comprises magnesia, so that each component in the ferrochrome slag is completely utilized.

The attached drawing is a process flow block diagram of the invention.

The chromium slag is soaked in water to obtain soluble hexavalent chromium Cr⁺⁶Adding into water solution, reducing and neutralizing to obtain Cr (OH)₃Precipitation, comprehensive utilization; in this case, the leaching residue mainly contains chromium oxide (Cr)₂O₃) Iron oxide (FeO; fe₂O₃) And high-quality magnesia brick refractory material (mainly comprising magnesia), because the specific gravity difference between the chrome oxide and the ferric oxide and the magnesia brick refractory material is larger, the chrome oxide and the ferric oxide can be separated from the magnesia brick refractory material by adopting a conventional physical separation means according to the difference of the specific gravity, and the separated chrome oxide and ferric oxide are subjected to reduction acid leaching treatment for deferrization to obtain high-grade chromite. In the reducing acid leaching treatment, since the iron oxide can be reduced to metal by the reducing agent at a lower temperature than the chromium oxide, in this way,by controlling the reduction conditions, most of iron nutrient in the chromium-containing minerals can be reduced into metallic iron, then the metallic iron is leached by dilute acid, the metallic iron is dissolved to generate soluble ferric salt, the chromium oxide is not dissolved and remains in the residue, thus obtaining the chromite, the main component of which is FeO&Cr₂O₃Or Fe (CrO)₂)₂Cr in ore₂O₃The content of (A) is generally about 45-60%. The reaction of the reduction acid leaching method is as follows:

the reducing agent can be carbon, coal powder, charcoal, coke, methane, blast furnace gas, natural gas and the like. The reducing temperature is slightly different with the reducing agent, generally 1250-1500 ℃, the acid leaching can use waste hydrochloric acid, and the temperature when leaching with sulfuric acid is generally 75-95 ℃.

The method has the obvious advantages of thoroughly solving the problem of treatment of the chromium leaching slag which cannot be solved for a long time, really changing waste into valuables, and changing the headache chromium leaching slag storage yard into high-grade chromite and CrO₃And a high-quality magnesia brick refractory material warehouse, and simultaneously, the process flow is simple, easy and reliable, the slag treatment amount is large, the investment is small, the effect is quick, the obvious social benefit and economic benefit are realized, and CrO can be obtained every 100 tons of chromium slag are treated₃About 2 tons, about 60 tons of high-quality magnesia brick refractory materials and about 10 tons of high-grade chromite.

Claims

1. A process flow for treating chromium leaching slag is characterized by comprising the following steps:

(1) leaching the chromium leaching slag with water to obtain the chromium-containing slag⁺⁶The solution of (a) and chromium slag containing chromium, iron oxide and magnesia brick refractory;

(2) containing Cr⁺⁶The solution is reduced, neutralized and filtered to obtain Cr (OH)₃) Precipitating, and separating the oxides of chromium and ironfrom the refractory magnesia brick material by using a physical separation method according to different specific gravities of the leached insoluble chromium slag;

(3) reducing the oxide of the chromium and the iron into metallic iron by reduction and acid leaching treatment, then dissolving and leaching the metallic iron by dilute acid, and obtaining the chromite after the oxide of the chromium is not dissolved and remained in the residue.

2. The process according to claim 1, wherein the reduction temperature is 1250-.

3. The process according to claim 1, wherein sulfuric acid or waste hydrochloric acid is used for acid leaching, and the temperature of sulfuric acid leaching is 75-95 ℃.