In recent years, North China, South China and other places have found a number of rich reserves of manganese ore containing silver, silver per ton of ore to several tens of kilograms, manganese 3% -35%, or accompanying a certain amount of iron, lead, zinc, magnesium, aluminum, barium, copper and other metal mineral, is a silver-containing multi-metal ore, is one of the important silver-containing ores, and have higher added value features extensive regional distribution . According to the type of manganese ore, it can be easily divided into oxidation type, sulfurization type, carbonate type and hydroxide type. The oxidation type is the main type of silver-containing polymetallic manganese ore currently proven, and it is mainly distributed on the surface or shallow layer. The type of ore that is easy to separate and difficult to separate.
The silver-bearing manganese ore in the form of oxides can be mainly used. The minerals are mostly embedded with fine grain size, and the silver is closely combined with minerals such as manganese and iron. It is difficult to effectively separate silver, manganese and iron by beneficiation method, and the ore cyanidation The leaching rate of immersion silver is generally less than 30%. This type of ore has been classified as a type of â€œstaying oreâ€ that is difficult to use [2-3] .
According to the nature of such ore, it is suitable to obtain the silver-manganese mixed concentrate by first mineral enrichment, and then carry out the hydrometallurgical leaching and purification treatment of the mixed concentrate, and further obtain a series of manganese such as manganese sulfate, manganese carbonate, electrolytic manganese and silver. And silver processed products. The high-efficiency beneficiation process not only ensures a high enrichment ratio, but also achieves a high comprehensive recovery rate, while reducing the hydrometallurgical treatment capacity and material consumption, and reducing the environmental treatment cost of hydrometallurgical residues.
First, the nature of the ore
(1) Analysis of mineral composition
The chemical multi-element analysis results of a silver-containing polymetallic manganese ore are shown in Table 1.
The X-ray diffraction pattern of the ore is shown in Figure 1. The results of phase analysis of manganese, iron and silver are shown in Tables 2 to 4.
The results of analysis and identification indicate that the metal minerals in the ore are mainly pyrolusite, manganese ore and hard manganese ore, followed by goethite, limonite, rhodochrosite, Zn-Mn ore, pyrite, galena, sphalerite, and hui. Silver mines, angle silver mines, natural silver, gold and silver mines, etc., are small to trace amounts. The gangue minerals are mainly quartz , followed by mica , feldspar , calcite , dolomite and clay minerals.
(2) Mineral inlay relationship
The soft manganese ore, manganese ore and hard manganese ore in the ore are the main manganese-bearing minerals in the ore and also the main carrier mineral of silver; the manganese ore is also replaced by goethite and limonite, and the iron ore is mostly distributed at the edge of the manganese ore. Venetian, worm-like, pinnate, concentric layered distribution; silver minerals are mostly encapsulated in minerals such as manganese and iron ore in the form of fine particles or adsorption, or in their micro-cracks, also see a small number of fine-grained veins. The stone is wrapped or distributed in the manganese oxide ore in the form of a homogeneous I.
Second, mineral processing enrichment
(1) Selection of enrichment options
1. Common and effective enrichment means for silver-containing polymetallic manganese ore. Silver-bearing manganese ore is an important type in manganese ore. China's manganese ore is characterized by lean, fine and heterogeneous. It is characterized by low manganese content, fine minerals such as manganese (iron) and gangue (the particle size is 10 Î¼m). Left and right), and a variety of associated minerals, it is difficult to obtain a separate manganese concentrate, silver concentrate by mechanical beneficiation method, it is also difficult to obtain better silver leaching index by first cyanidation or conventional immersion silver method. Therefore, the treatment method of silver-containing polymetallic manganese ore generally adopts multi-metal aggregate dressing, which is characterized by high recovery rate of main elements, but the grade of concentrate is not too high, and the selection process can adopt strong magnetic separation, re-election method, floating Selection method, etc.; due to the high mud content of manganese ore, washing and sieving are also common methods, which not only have a certain enrichment effect, but also provide convenience for further selection; in addition, there is a fire method to enrich a manganese-rich Slag method, chemical beneficiation and other methods [4-5] .
2. The grinding operation before enrichment should avoid excessive pulverization of materials. Since the silver-containing polymetallic manganese oxide ore is mostly distributed on the surface or in the shallow layer, the ore is weathered and pulverized seriously and the muddy rate is high. The raw ore of the test is sieved by particle size analysis, and the coarser the particle size, the higher the grade of manganese and silver. Exploratory experiments show that the strong magnetic separation process can economically and efficiently enrich the silver and manganese minerals into the mixed concentrate, and the recovery effect on the coarse fraction is significantly higher than that on the fine fraction, so the grinding before the enrichment Work should try to avoid excessive crushing of ore.
3. Grading - The strong magnetic separation process for wet and dry separation is an efficient process for the mine. Exploratory experiments show that the use of all-wet strong magnetic separation, the concentrate grade is higher, but the recovery rate of manganese and silver is low; while the full dry strong magnetic separation, the recovery rate of silver manganese is high but the concentrate grade is low. table 5.
Although dry strong magnetic separation has the characteristics of high recovery rate of silver and manganese, high productivity and low cost, it is difficult to achieve high tailing efficiency for the ore containing fine-grained grades. Therefore, the manganese and silver grades of concentrates are not necessarily high. In order to ensure a higher comprehensive index of manganese and silver, the process of grading, dry and wet magnetic separation was finally determined.
(2) Research on strong magnetic separation enrichment process
According to the properties of the silver-containing polymetallic manganese ore and the characteristics of the strong magnetic separation equipment , the process of dry screening and classification-coarse-grained strong magnetic separation-fine-grain wet magnetic separation was established. The test procedure and results are shown in Figure 2. The results of multi-element analysis of concentrates are shown in Table 6.
Figure 2 and Table 6 show that the process of dry screening and grading-coarse-grained strong magnetic separation-fine-grain wet magnetic separation of the silver-containing polymetallic manganese ore is thrown out of nearly 40% of the tailings. In the case, the recoveries of the main beneficial elements Mn and Ag exceeded 90%, the manganese grade increased by nearly 11 percentage points, the Ag grade increased by 204.8 g/t, and the iron grade increased by 2.34 percentage points, so that the metallurgical leaching of raw materials was manganese. The content of beneficial elements such as silver and silver has been greatly improved, and the amount of metallurgical leaching raw materials has dropped significantly, laying a foundation for the subsequent efficient recovery of beneficial elements.
Third, the conclusion
(1) A silver-containing polymetallic manganese ore is a complex manganese ore with high added value and fine particle inlay. Under the current technical conditions, physical methods are difficult to effectively dissociate manganese and silver.
(2) According to the mineral inlay and symbiosis characteristics of the ore, the first classification and re-magnetic separation can effectively enrich the silver and manganese minerals into the mixed concentrate, creating a hydrometallurgical economy and efficient leaching of manganese and silver. condition.
(3) Experimental studies have shown that the coarse-grained grade of the mineral is suitable for dry strong magnetic separation, while the fine-grain grade is suitable for wet strong magnetic separation. In the preparation of the magnetic separation material, the excessive pulverization of the mineral should be avoided as much as possible.
(4) Using the dry sieving grading-coarse dry-type strong magnetic separation-fine-grain wet-type strong magnetic separation process, the mixed concentrate with high manganese and silver grade and recovery rate can be obtained, and the manganese and silver grades are respectively The recovery rates reached 31.59% and 657.9 g/t, and the recovery rates reached 90.24% and 91.29% respectively. In this enrichment process, the non-main element iron enrichment behavior was not obvious.
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