The vast majority of manganese ores in China belong to lean ores, and most of them are processed by beneficiation. However, most manganese ores are fine-grained or fine-grained, and there are a considerable number of high phosphorus ores, high iron ores and symbiotic beneficial metals, which brings great difficulty to beneficiation and processing. At present, the commonly used manganese ore beneficiation methods are mechanical beneficiation (including ore washing, screening, gravity separation, high-intensity magnetic separation and flotation), fire enrichment, chemical beneficiation, etc.

1. Ore washing and screening

Ore washing is the separation of ore and mud by hydraulic flushing or additional mechanical scrubbing. Common equipment includes ore washing screen, cylindrical ore washing machine and trough ore washing machine.

Ore washing is often accompanied by screening, such as washing directly on the vibrating screen or sending the ore (clean ore) obtained by the ore washer to the vibrating screen for screening. Screening can be used as an independent operation to separate products with different particle sizes and grades for different purposes.

2. Reselection

At present, gravity separation is only used to separate manganese ores with simple structure and coarse embedded particle size, especially for manganese oxide ores with high density. Common methods include heavy medium beneficiation, jigging beneficiation and shaking table beneficiation.

At present, the process flow of manganese oxide ore treatment in China is generally crushing the ore to 6 ~ 0mm or 10 ~ 0mm, then grouping, jigging for coarse grade and shaking table for fine grade. The equipment is mostly Hartz reciprocating jig and 6-s shaking table.

3. High intensity magnetic separation

Manganese minerals are weakly magnetic minerals [specific magnetic coefficient X = 1010-6 ~ 60010-6cm3 / g]. They can be recovered in a strong magnetic field magnetic separator with magnetic field intensity ho = 800 ~ 1600kA / M (10000 ~ 20000oe), which can generally increase the manganese grade by 4% ~ 10%.

Due to its simple operation, easy control and strong adaptability, magnetic separation can be used for the separation of various manganese ores. In recent years, it has occupied a * * * position in manganese ore dressing. Various new types of coarse, medium and fine strong magnetic machines have been successfully developed. At present, medium size high-intensity magnetic separators are Zui widely used in domestic manganese ores, coarse and fine-grained high-intensity magnetic separators are also gradually applied, and fine-grained high-intensity magnetic separators are still in the experimental stage.

4. Gravity magnetic separation

At present, the newly-built and reconstructed gravity magnetic separation plants in China include manganese mines in Liancheng, Fujian, Longtou, Jingxi and Xialei, Guangxi. For example, Liancheng Manganese Mine gravity magnetic separation plant mainly processes leaching manganese oxide ore, and uses am-30 jig to treat 30 ~ 3mm washed ore, which can obtain manganese concentrate containing more than 40% manganese. After manual separation and impurity removal, it can be used as raw material of battery manganese powder. After jigging tailings and washed ore diameter less than 3mm are grinded to less than 1m, they are separated by high-intensity magnetic separator. The grade of manganese concentrate should be increased by 24% ~ 25% to 36% ~ 40%.

5. Strong magnetic flotation

At present, strong magnetic flotation process is adopted to * * * Zunyi manganese ore. The ore is a low manganese, low phosphorus and high iron manganese ore dominated by manganese carbonate ore.

According to the industrial test, the grinding process adopts rod grinding ball milling stage, and the equipment scale is φ 2100mm 3000mm wet mill. Shp-2000 strong magnetic separator is used for strong magnetic separation, and CHF inflatable flotation machine is mainly used for flotation machine. After years of production, it has good performance and is very suitable for the application of manganese beneficiation in Zunyi. The successful test of strong magnetic flotation process and its application in production indicate that the deep separation of manganese ore in China has taken a big step forward.

6. Fire enrichment

Pyrometallurgical enrichment of manganese ore is a separation method for treating refractory lean manganese ore with high phosphorus and high iron, which is generally called manganese rich slag method. Its essence is a high-temperature separation method for selective separation of manganese, phosphorus and iron by controlling their temperature in blast furnace or electric furnace.

Fire enrichment has been used in China for nearly 40 years. In 1959, Hunan Shaoyang Zijiang iron works carried out tests on a 9.4m3 small blast furnace and obtained preliminary results. Subsequently, in 1962, Shanghai ferroalloy plant and Shijingshan iron and steel plant smelted manganese rich slag in blast furnace respectively. In 1975, the blast furnace of Manaoshan manganese mine in Hunan not only smelted manganese rich slag, but also recovered lead, silver and pig iron (commonly known as semi steel) at the bottom of the furnace, providing a basis for comprehensive utilization. After entering the 1980s, the production of manganese rich slag has developed rapidly, and the production of manganese rich slag has been developed in Hunan, Hubei, Guangdong, Guangxi, Jiangxi, Liaoning, Jilin and other places.

Pyrometallurgical enrichment process is simple and stable. It can effectively separate iron and phosphorus from ore to obtain manganese rich, low iron and low phosphorus manganese rich slag. This manganese rich slag generally contains mn35% ~ 45%, Mn / fe12 ~ 38, P / Mn < 0.002. It is a kind of * * * manganese alloy raw material. At the same time, it is also an artificial rich ore of general natural manganese rich ore, which is difficult to meet the above three indexes at the same time. Therefore, pyrometallurgical enrichment is a promising beneficiation method for difficult beneficiation of high phosphorus, high iron and low manganese in China.

7. Chemical manganese separation

There are a lot of chemical beneficiation of manganese. A lot of research work has been carried out in China, among which there are many tests. The more promising ones are continuous bisulfate method, black manganese ore method and bacterial manganese leaching method. At present, it has not been put into industrial production.