Method for preparing chromium salt

Abstract

The invention discloses a method for preparing chromium salt. The method is characterized by comprising the following steps: sufficiently and uniformly mixing a raw material containing chromium oxide (chrome ore or chromium slag) with sodium carbonate, carrying out oxidizing roasting at the roasting temperature of 900-1100 DEG C for 0.5-2.5 hours in an atmosphere with the oxygen content of higher than 20% by using microwaves as a heat source, leaching the roasted product with water, and preparing chromium salt from the leach solution. The chemical analysis on the clinker and leaching slag indicates that the insoluble waste slag contains less than 5% of chromium (on the basis of chromic oxide). The method reduces the chromium content in the discharged chromium slag, enhances the chromium utilization ratio in the chromium salt production process, effectively saves the chrome ore resources, and has obvious advantages of resource saving and environmental protection by using the microwaves as the heat source instead of the traditional coal and natural gas heating.

Description

technical field

[0001] The invention belongs to the technical field of chromium slag treatment, and in particular relates to a method for preparing chromium salt. Background technique

[0002] Chromium slag is the main industrial waste slag produced during the production of chromium salts. It is a highly toxic and hazardous waste. If it is not treated for a long time, it will seriously pollute the ecological environment and endanger various organisms. Recycling chromium in chromium slag is very important for pollution control and The comprehensive utilization of chromium slag resources has important practical significance.

[0003] Chromium salt is produced by mixing chromium ore with soda ash and roasting at high temperature. Metal chromium is produced from water-insoluble trivalent chromium to water-soluble hexavalent chromium, so as to achieve the purpose of separating metal chromium from gangue. The traditional heating method The temperature condition of the reaction is...

Examples

Embodiment 1

[0034] Mix chromium ore and industrial soda ash at a ratio of 100:90 to obtain a mixture. In an atmosphere with an oxygen content of 20-23%, use microwaves with a frequency of 2400-2500MHz to heat and roast the mixture. The roasting temperature is 1050°C and the roasting time is 1.5h. Roasted clinker is obtained, and the obtained roasted clinker is immersed in water to obtain a leaching solution for the preparation of chromium salts; the clinker and leaching residue are chemically analyzed, and the insoluble waste residue contains 2.5% chromium (calculated as chromium trioxide), and the chromium leaching rate is 85%. The utilization rate of chromium in the preparation of chromium salt is 95%; the total utilization rate of chromium in chromium slag reaches 100% by combining with the detoxification blast furnace of chromium slag.

Embodiment 2

[0036] Mix chromium slag and industrial soda ash at a ratio of 100:120, and statically roast in a microwave oven with an electromagnetic wave frequency of 890-940MHz in an oxygen-rich atmosphere with an oxygen content of 23-25%. The roasting temperature is 1000°C and the roasting time is 1.5 h to get roasted clinker, water extraction gained roasted clinker to obtain leachate for the preparation of chromium salt; clinker and leaching residue through chemical analysis, insoluble waste residue chromium (calculated as dichromium oxide) is 2%, chromium leaching rate 92%; the utilization rate of chromium in the preparation of chromium salt is 98%, and the total utilization rate of chromium in the chromium slag reaches 100% by combining with the chromium slag detoxification blast furnace.

Embodiment 3

[0038] Mix chromium slag and industrial soda ash at a ratio of 100:130, and statically roast in a microwave oven with an electromagnetic wave frequency of 890-940MHz in an oxygen-rich atmosphere with an oxygen content greater than 30%. The roasting temperature is 1100°C and the roasting time is 1.5h. Obtain roasted clinker, the gained roasted clinker of water leaching obtains leaching solution and is used for preparing chromium salt; After chemical analysis of clinker and leaching slag, the insoluble waste residue containing chromium (calculated as dichromium oxide) is 2.5%, and the chromium leaching rate is 95%. %; The utilization rate of chromium in the preparation of chromium salt is 99%, and the total utilization rate of chromium in chromium slag reaches 100% by combining with the blast furnace for detoxifying chromium slag.

technical field

[0001] The invention belongs to the technical field of chromium slag treatment, and in particular relates to a method for preparing chromium salt. Background technique

[0002] Chromium slag is the main industrial waste slag produced during the production of chromium salts. It is a highly toxic and hazardous waste. If it is not treated for a long time, it will seriously pollute the ecological environment and endanger various organisms. Recycling chromium in chromium slag is very important for pollution control and The comprehensive utilization of chromium slag resources has important practical significance.

[0003] Chromium salt is produced by mixing chromium ore with soda ash and roasting at high temperature. Metal chromium is produced from water-insoluble trivalent chromium to water-soluble hexavalent chromium, so as to achieve the purpose of separating metal chromium from gangue. The traditional heating method The temperature condition of the reaction is...

Examples

Embodiment 1

[0034] Mix chromium ore and industrial soda ash at a ratio of 100:90 to obtain a mixture. In an atmosphere with an oxygen content of 20-23%, use microwaves with a frequency of 2400-2500MHz to heat and roast the mixture. The roasting temperature is 1050°C and the roasting time is 1.5h. Roasted clinker is obtained, and the obtained roasted clinker is immersed in water to obtain a leaching solution for the preparation of chromium salts; the clinker and leaching residue are chemically analyzed, and the insoluble waste residue contains 2.5% chromium (calculated as chromium trioxide), and the chromium leaching rate is 85%. The utilization rate of chromium in the preparation of chromium salt is 95%; the total utilization rate of chromium in chromium slag reaches 100% by combining with the detoxification blast furnace of chromium slag.

Embodiment 2

[0036] Mix chromium slag and industrial soda ash at a ratio of 100:120, and statically roast in a microwave oven with an electromagnetic wave frequency of 890-940MHz in an oxygen-rich atmosphere with an oxygen content of 23-25%. The roasting temperature is 1000°C and the roasting time is 1.5 h to get roasted clinker, water extraction gained roasted clinker to obtain leachate for the preparation of chromium salt; clinker and leaching residue through chemical analysis, insoluble waste residue chromium (calculated as dichromium oxide) is 2%, chromium leaching rate 92%; the utilization rate of chromium in the preparation of chromium salt is 98%, and the total utilization rate of chromium in the chromium slag reaches 100% by combining with the chromium slag detoxification blast furnace.

Embodiment 3

[0038] Mix chromium slag and industrial soda ash at a ratio of 100:130, and statically roast in a microwave oven with an electromagnetic wave frequency of 890-940MHz in an oxygen-rich atmosphere with an oxygen content greater than 30%. The roasting temperature is 1100°C and the roasting time is 1.5h. Obtain roasted clinker, the gained roasted clinker of water leaching obtains leaching solution and is used for preparing chromium salt; After chemical analysis of clinker and leaching slag, the insoluble waste residue containing chromium (calculated as dichromium oxide) is 2.5%, and the chromium leaching rate is 95%. %; The utilization rate of chromium in the preparation of chromium salt is 99%, and the total utilization rate of chromium in chromium slag reaches 100% by combining with the blast furnace for detoxifying chromium slag.