Manganese and its compounds are used in various fields of the national economy. Manganese steel industry accounts for 90% to 95%, mainly iron and steel making process as deoxidizer and desulfurizer, and means for producing an alloy.
With the development of China's iron and steel industry and the increase in the export of manganese products, the consumption of manganese ore has gradually increased, and the proportion of imported ore is increasing. In 2002, the imported manganese ore exceeded 2 million tons for the first time, accounting for the total of China. The consumption of manganese ore is 45.81%. If the grade of imported ore is higher than that of domestic manganese ore, the manganese content of imported ore has exceeded 50% of the total consumption of domestic manganese metal. The gap in domestic ore supply is more The bigger it is. Therefore, while making full use of foreign resources, it is necessary to speed up the exploration of domestic manganese ore resources, increase the depth of exploration, and vigorously study manganese ore processing and impurity removal ( phosphorus , sulfur) technology.
The content of phosphorus in manganese ore in China is relatively high, and the average P/Mn is about 0.01, while the manganese ore for metallurgy requires P/Mn<0.003, which is a high-phosphorus manganese ore. Among the mineral deposits surveyed, the phosphorus content exceeded the standard by 49.6%, and the high-quality manganese ore standard accounted for about 6%. Phosphorus in manganese ore mainly exists in the form of apatite or collophosphate. Phosphorus mineral inlays have fine grain size or exist as endoplasmic with manganese minerals, and it is difficult to achieve monomer dissociation 3 .
China's high-phosphorus-poor manganese carbonate ore is mainly distributed in the border areas of Hunan, Yunnan and Sichuan provinces, including Hunan Huayan manganese mine, Guizhou Songtao manganese mine, Sichuan Xiushan manganese mine, etc. The total reserves are about 100 million tons, and this type of manganese ore contains P0.24. About 9%, Mn 18% to 19%, and P/Mn is about 0.01.
Phosphorus is one of the most harmful elements in the iron and steel smelting process. Too high phosphorus content in metallurgical manganese ore will directly affect the variety and quality of steel. Combined with the comprehensive utilization of high-phosphorus manganese ore, research on economical and effective dephosphorization technology is an important issue.
I. Status of dephosphorization technology for high-phosphorus manganese ore
At home and abroad, for the different ore properties, a deeper study on the dephosphorization process of manganese ore was carried out. The main methods are: strong magnetic separation, reverse flotation, strong magnetic separation, roasting, strong magnetic separation, a black manganese ore, reduction-ammonia leaching, and microbial dephosphorization.
(1) Strong magnetic selection and reverse flotation
Reverse flotation is still the most important method for dephosphorization of manganese ore. In order to reduce the cost of reverse flotation or further reduce the phosphorus content, magnetic separation-reverse flotation combined with dephosphorization has shown advantages.
In the anti-flotation dephosphorization of manganese ore, oxide wax is generally used as a collector, and NaOH, Na 2 SiO 3 and Na 2 CO 3 are used as adjusting agents, and starch is used as an inhibitor. At the same time, the use of GY-1 agent is added. GY-1 is an efficient, non-toxic, non-corrosive and easy-to-use anionic surfactant based on DC-854. It has good selection in reverse flotation. Sexual dispersion, and has a significant effect on improving product quality. The P/Mn of high-phosphorus manganese ore in a certain area of ​​western Hubei is 0.046, and the P/Mn is 0.002, manganese can be obtained by deliming, strong magnetic separation, 1 reverse flotation dephosphorization and 3 times foam re-selection dephosphorization. The grade is 78.87% of the final manganese concentrate index.
(2) Strong magnetic separation and roasting
Xiangtan manganese ore is a low-iron, high-phosphorus-poor manganese carbonate deposit, and its phosphorus-bearing mineral is a collo-phosphorus ore, which is present in clay minerals. Manganese carbonate is a weak magnetic mineral, and clay minerals are non-magnetic minerals. The magnetic difference is selected by strong magnetic separation, and then calcined to achieve manganese-rich phosphorus-reducing effect.
The Xiangtan manganese ore was continuously tested by strong magnetic separation. The ore contains Mn21.95% and a particle size of 7-10 mm. After 1 roughing and 1 selection, manganese concentrate I contained 27.70% Mn, the recovery rate was 38.5%; manganese concentrate II contained Mn 23.7%, the recovery rate was 55.94%, and the total recovery rate was 94.44%. After the magnetic manganese ore was calcined, the concentrate I contained 42.6% Mn and P/Mn was 0.003 9; the concentrate II contained Mn 35.03% and P/Mn was 0.0049.
(3) Strong magnetic separation of a black manganese ore
Hunan Huayan Manganese Mine is a large-scale manganese carbonate mine in China. It is characterized by low manganese and high phosphorus. The mineral inlay has a fine grain size and is a difficult manganese ore. The manganese ore is subjected to strong magnetic separation and a black manganese ore method for dephosphorization and strong magnetic separation. The demineralization process of the black manganese ore is carried out. After the ore is crushed to a certain particle size, it is classified by a coarse-grained and fine-grained strong magnetic separator, and dehydrated for boiling roasting. The calcined product is fed to a continuous leaching machine for dephosphorization, and finally the solid-liquid separation is carried out to obtain a final concentrate.
The process is characterized by coarse particle size, good magnetic separation and tailing effect, uniform calcination temperature, high conversion rate of roasting manganese ore, short acid residence time and simple operation. Studies have shown that the continuous expansion test has achieved the same results as the small test, the comprehensive concentrate yield is 40.85%, the concentrate manganese grade is 40.15%, the manganese recovery rate is 82.071%, and the phosphorus-manganese ratio is 0.003 7.
(4) Dephosphorization outside the furnace
The dephosphorization method outside the furnace is to refine the manganese ore or sinter with high phosphorus content into a silicon-manganese alloy in an electric furnace, put the hot alloy into the ladle outside the furnace, and then add a dephosphorization agent thereto, and then oscillate the reaction. The phosphorus in the alloy is removed.
The Huayan manganese ore has been subjected to dephosphorization test outside the furnace, and the dephosphorization rate reached 76.84%. The Changsha Metallurgical Research Institute made a 0.91% silicon-manganese alloy with a sinter containing higher phosphorus. After dephosphorization treatment, the phosphorus content of the alloy decreased to 0.19%. The process utilizes waste heat, and the product cost is not increased much, and the high-quality silicon alloy is obtained, which is worthy of popularization and application.
(5) reduction roasting-ammonia dip
This method has been used in the treatment of low-grade manganese ore for decades. In the 1950s, American Manganese Chemical Company and Sedema Company of Belgium established an ammonia leaching plant for treating manganese ore, and ammonia leaching method for manganese production as production chemistry. The raw material of manganese dioxide has achieved good results.
In China, since the 1980s, the experiment of extracting manganese from ammonia leaching has been started. In 1983, Guizhou Zunyi Ferroalloy Research Institute proposed a scheme for treating Guizhou Songtao high-phosphorus manganese ore by reduction roasting and ammonia leaching. In 1984, the Institute of Metallurgical Materials of Hunan Province also reported the preliminary test results of treatment of high-phosphorus manganese ore by alfalfa.
The Guizhou Songtao high-phosphorus manganese ore is dephosphorized by reduction roasting and ammonia leaching. The process includes crushing, roasting, leaching, solid-liquid separation, recovery of manganese from the leachate, and regeneration and recycling of the solvent. The leaching rate of manganese is 73.2% to 89.6%, the product contains 70% to 72% of manganese, and the product contains less than 0.02% of phosphorus.
(6) Microbial dephosphorization
Biotechnology is one of the emerging industries with faster development. Biotechnology has gradually demonstrated its strong advantages due to its low energy consumption and pollution-free characteristics. In nature, the distribution of more than 60 elements is related to microorganisms. Microorganisms participate in the dispersion, oxidation, and reduction of various elements such as S, Fe, C, N, P, Cu, Si, and Mn. The microbial treatment of wastewater and the removal of phosphorus have been successful, indicating that the microorganisms have the ability to dephosphorize.
In recent years, research on the use of microorganisms to treat mineral resources has been very active. A variety of bacteria, fungi, and actinomycetes have been found to have dephosphorization. They mainly reduce the pH of the system by metabolic acid production, so that the phosphorus mineral dissolves into the liquid phase. At the same time, the metabolic acid production also forms complexes with Ca 2 + , Mg 2 + , Al 3 + ions, thereby promoting the dissolution of phosphorus minerals. Studies have shown that some bacteria have the characteristics of excessive phosphorus uptake, which is one of the mechanisms of microbial dephosphorization.
The research progress of microbial dephosphorization at home and abroad is shown in Table 1.
2. Prospects for dephosphorization technology of high phosphorus manganese ore
The development of modern industrial technology must follow the scientific development concept that the comprehensive utilization of resources is high, the degree of environmental pollution is low, and it is in line with the construction of a conservation-oriented society. The research on dephosphorization technology of high-phosphorus manganese ore should pay special attention to improving the recovery rate of manganese, reducing the energy consumption and water consumption in the process, reducing the consumption of various chemical reagents, and achieving as much as possible in the effective dephosphorization technology. The process is harmless and does not cause environmental pollution.
In the existing research, the reverse flotation consumes a large amount of water, the grinding process consumes a lot of power, and at the same time, a variety of flotation reagents are used. The strong magnetic separation requires a good monomer dissociation of the mineral, and the solid mineral The sorting effect is poor. The strong magnetic separation of a black manganese ore method has a long process flow and complicated operation. The dephosphorization process outside the furnace needs to be dephosphorized at high temperature, which is inconvenient to operate.
Looking at the research results of dephosphorization of high-phosphorus manganese ore, it seems that it is a reduction of roasting-ammonia leaching method and microbial dephosphorization technology. In comparison, microbial dephosphorization technology has advantages and deserves in-depth research and attention. The research on microbial dephosphorization technology should pay attention to the following aspects:
(1) When screening dephosphorization microorganisms, it is based on whether it has biochemical characteristics of acid production and accumulation of phosphorus. In the dephosphorization of ore, promoting the progress of these two processes is the key to strengthening the dephosphorization effect;
(2) There are many kinds of dephosphorization microorganisms, and the decomposition mechanism is different and complicated. Although there are some studies, but there is no deepening, the dephosphorization mechanism needs to be further clarified;
(3) The genetic stability of dephosphorus microorganisms is poor, and attention should be paid to finding microorganisms with good stability. For some dephosphorization microorganisms with excellent traits, they should be continuously screened and rejuvenated to improve their dephosphorization ability;
(4) To make the dephosphorization microorganisms better adapt to the environment provided by the high-phosphorus-poor manganese ore, such as enhancing the microbial resistance to fluoride ions and possible heavy metal ions, and increasing their quantity and activity;
(5) Dephosphorization microorganisms are mostly heterotrophic bacteria, and searching for cheap organic carbon sources (such as carbohydrates) can improve the economics of the technology.
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