As in recent years, strong, improve efficiency of the sector of the market price of vanadium pentoxide, a variety of vanadium extraction technologies are emerging, now divided into two factions: one wet vanadium extraction method, two for vanadium extraction Fire law.
The wet vanadium extraction technology is mainly developed by a research institute under the Ministry of Nuclear Industry, also known as acidification and vanadium extraction technology. This technology has strong selectivity to ore and consumes a large amount of acid in production. It requires 15 to 25 tons of sulfuric acid for 100 tons of ore. In the liquid treatment, the liquid needs to be adjusted to neutral, so that the alkali consumption is also high, and the raw materials in the middle of the cost are too high, and the stacking of the waste residue causes certain pollution to the environment. The scale application of this technology is part of the vanadium plant in Shanyang, Shaanxi Province. In 2006, it was compulsory to be closed due to serious pollution. The fire method was to pass the ore to roast and then leaching to extract vanadium. The key to this technology is the difference between the calcination method and the additive. Now we have an overview of the roasting methods that have emerged in recent years in China, for your company's reference. When selecting the process route, take less detours. Please correct me if there are any deficiencies.
First, flat kiln roasting method
The flat kiln roasting method is a classic roasting method. After a long time of practice test, it is a more practical method of roasting, and at the same time found its shortcomings in practice. The biggest disadvantage is that the rate of conversion is unstable, and the deviation of conversion rate is high throughout the year, which is also biased in one day. This is mainly due to the different speeds of the airflow. Since the roasting method is to pre-distribute the calorific value of the mineral material, if the speed of the airflow rises, it is controlled only by adjusting the chimney damper. This kind of adjustment method is difficult to find the best point, so the conversion rate of roasting can only be stable between 40% and 50%.
Second, multi-hearth roasting method
Earliest multi-hearth furnace for calcination Panzhihua vanadium steel industry is a company, for roasting vanadium slag, vanadium slag firing temperature of the high temperature zone of 720 ~ 800 ℃ in production. In 2006, Chenxi Hongda Vanadium Industry Co., Ltd. also adopted this roasting method in production, but the effect was not satisfactory. The main reason for this result was that the ore stayed in the high temperature section. Vanadium stone coal mine high-temperature stage with the optimum calcination temperature is relatively narrow, the amplitude variation is only 10 ~ 20 ℃, and because the vanadium in the firing process is a continuous process of conversion and oxidation, the optimum temperature required to stay at the point 5-6 In hours, you can reach the highest conversion rate. In this method of calcination, the calorific value is pre-configured, and the temperature is adjusted by the amount of air that is blown in. From top to bottom, it is a process of continuously consuming heat. It is not feasible to stay for 5-6 hours at a certain temperature point. Therefore, this furnace to be used for roasting vanadium containing stone coal mine, also requires a lot of practice to adjust the industry.
Third, boiling furnace roasting method
At present, the boiling furnace is used in the vanadium-bearing industry of vanadium-bearing coal mines. The success is only in the step of decarburization of ore, and the conversion rate is only below 10%. So far, we have not seen cases where the conversion rate is above 40%. Although there are many patented technologies for boiling boilers containing vanadium-bearing coal mines, there are only a few words, which are rarely used in production practice and have great risks. The boiling furnace roasting vanadium-bearing coal mine has the difficulty that the residence time of the ore in the furnace is too short, and the residence time is extended. Only the volume of the boiling furnace is infinitely expanded, and this scheme has a large investment risk. Another disadvantage of boiling furnace roasting is that the contact between the mineral material and the additive is insufficient, and the ideal conversion rate is not achieved. This roasting method requires a large amount of practice and technical improvement to determine its economy.
Fourth, rotary kiln roasting method
Rotary kiln roasting method is used in the vanadium pentoxide vanadium extraction industry. The earliest in China is the roasting of vanadium slag by Panzhihua Iron and Steel Company of Sichuan. The high temperature section of roasting is 720-800 °C, and a certain amount of sodium carbonate is added to the vanadium slag. Long flame burner, the length of the high temperature section is about 20 meters, and the conversion rate of vanadium is above 90%. The roasting principle is that the vanadium slag is fired into a melt under the action of sodium carbonate, and the vanadium is converted into sodium vanadate. The vanadium slag does not need to be in the furnace for a long time; the other point is that the vanadium slag generally has a vanadium content of 20%. The ratio of the additive to the amount of vanadium is small. The vanadium content of the vanadium-bearing coal mine is generally about 1%. If it is added according to the ore content of 12-15%, the cost is too high; the second is that some ore is not necessarily suitable for adding sodium carbonate. In 2000, I used the vanadium mine of the autonomous prefecture and the original rotary kiln that burned strontium sulfide for two months at Jishou Building Chemicals General Factory. The result was unsuccessful. The following conclusions were reached through practice: To achieve the best conversion rate of ore, the ore is in The residence time of the high temperature section of 930 °C is maintained at 5 to 6 hours, while the rotary kiln should be burned normally at a low temperature of at least 1100 ° C, and the melting point of the ore does not exceed 1000 ° C, so the ore conversion rate is optimal. The calcination temperature limits the normal combustion of the rotary kiln.
To overcome this drawback, multiple fire points must be taken. According to the size of the output, it is necessary to increase 5 to 10 fire-breathing points. One fire-breathing point needs one fulcrum. The original rotary kiln has three sets of supporting wheels. If the fire-breathing point is increased, 8 to 13 fulcrums should be made. In the state of heating and receiving weight, it runs in a straight line. From the perspective of mechanical design and manufacturing, it cannot be used in actual production of the enterprise without a lot of experiment and practical application. Therefore, this roasting method is used at this stage. The actual production and construction investment is too large, and the risk is extremely high. It can only be used after the practice is mature.
Five, step type roasting method
I designed a new type of furnace-stepping roaster by combining the firing principle of various furnace types with the mechanism of obtaining the best conversion rate of vanadium-bearing coal mine.
This type of furnace has been produced on a large scale in Pingdingshan, Henan Province. The average conversion rate of ore is stable at more than 70%. No matter which type of furnace has its advantages and disadvantages, it is now a production facility with more than one year. The advantages and disadvantages of the performance are summarized as follows: Advantages 1. Low dust and good working environment. 2, the roasting pass rate is high, generally above 98%. 3, no burning materials can return to re-burn. 4. The ore and additive calcium salt are in full contact, and the conversion rate is generally stable at more than 70%. 5, the degree of mechanization is high, avoiding the impact of weather, human factors, etc. on conversion rate, production personnel save nearly 40% than the personnel required for flat kiln production. 6, easily controlled, a stable production disadvantage requires external heat energy utilization rate of 100 tons of coal 2 5 tons of ore for an investment relatively flat kiln, the same need to increase the size by 10% funding
Conclusion
From the current non-oxidized vanadium roasting process, the successful furnace type is only the flat kiln and the step-type baking furnace we developed. It takes some time for other furnace types to be applied in practice.
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