Because of the large amount of lean ore (accounting for 97.5% of the total reserves) and comprehensive ore which associated with other components (accounting for one-third of the total reserves) in our country, most of the iron ore needs dressing process before smelting. In 1996, the selected iron ore was 214.97 million tons which accounts for 85.2% of the amount of undressed ore production of 252.28 million tons.
Next, experts from Henan Hongxing Mining Machinery Co., Ltd will give a detailed introduction to its beneficiation technology and equipment used of the Ore processing plant.
1. Rock crushing:
The dressing plants in our country generally use such three sections of crushing process as coarse, medium and fine breaking to crush it. For the coarse crushing, 1.2m or 1.5m spinning back crusher is used; 2.1 m or 2.2 m standard cone breaker for medium breaking, and 2.1 m or 2.2 m short-headed type cone crusher for fine crushing. The ore after coarse breaking has below 1m of lumpiness, and then through medium and fine grinding, it will be screened for finished products with granularity less than 12mm and then transported to the grinding slots.
2. Rock grinding:
Most of the grinding technology in our country uses two paragraphs process and for small and medium-sized concentrator, they use one stage process.
Iron ore concentrator preparation
Very low grade Iron ore cannot be used in metallurgical plants and needs to be upgraded to increase the iron content and reduce the gangue content. A process adopted to upgrade ore is called Beneficiation. Iron ore is upgraded to higher iron content through concentration. Iron ore is being beneficiated all round the world to meet the quality requirement of Iron and Steel industries. However, each source of Iron ore has its own peculiar mineralogical characteristics and requires the specific beneficiation and metallurgical treatment to get the best product out of it. The choice of the beneficiation treatment depends on the nature of the gangue present and its association with the ore structure. Several techniques such as washing, jigging, magnetic separation, advanced gravity separation and flotation are being employed to enhance the quality of the Iron ore.
Due to the high density of hematite relative to silicates, beneficiation usually involves a combination of crushing and milling as well as heavy liquid separation. This is achieved by passing the finely crushed ore over a bath of solution containing bentonite or other agent which increases the density of the solution. When the density of the solution is properly calibrated, the hematite will sink and the silicate mineral fragments will float and can be removed.
Ore beneficiation technology
(1) Magnetite dressing technology
It is mainly used for Ore separating line with low taste. Because the rocks have a strong magnetism and easy to grinding, most of the magnetic ore-dressing plants adopt one stage and many stages process for its crushing and grinding. Later, our country independently researched and developed eternal magnetization technology for the magnetic separator. After the 1960s, the new technology of fine screening and grinding again makes the concentrate grade improve to about 66% from 62%, thus realizing the requirement by the Ministry of Metallurgical Industry that the concentrate grade has to be improved to 65%.
(2) Multi-metal associated ore beneficiation:
This kind of rocks have complicated component and diversified types, so that the methods, equipment and production process are different. For example, In Panzhihua, plants there gained about 53% ferrovanadium concentrate through magnetic separation, and the gangue is disposed through light porcelain scavenging, double beneficiation, flotation and drying electricity selection and in the end, titanium and cobalt concentrate are gained.
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