Jaw Crusher Circuit,Primary Crusher Circuit,Primary Crushing Plant

Primary jaw crushers typically operate in open circuit under dry conditions.Depending on the Size reduction required, the primary jaw crushers are followed by secondary and tertiary crushing. The last crusher in the line of operation operate sin closed circuit. That is,the crushed product is screened and the oversize returned to the crusher f furthe rsizereduction while the under size is accepted as the product.

Primary Crushing Plant

When the run of mine product is conveyed directly from the mine to the crusher, the feed to The primary crusher passes under a magnet to remove tramp steel collected during the mining operation. Agrizzly screen is placed between the magnet and the receiving hopper of the crusher to scalp (remove) boulders larger than the size of the gape. Some mines deliver product direct to storage bins or stockpiles, which then feed the crushers mechanically by apron feeders, Ross feeders or similar devices to regulate the feed rate to the crusher. Alternately haulage trucks, front-endloaders, bottomd ischarge railroad cars or tipping Wagons are used. In such cases, the feed rate to the crusher is intermittent which is a situation Generally avoided. In such cases of intermittent feed ,storage are s are installed and the feed Rate regulated by bulldozers, front loaders or bin or stockpile hoppers and feeders. It is Necessary that the feed to jaw crushers be carefully designed to balance with the throughput Rate of the crusher. When the feed rate is regulated to keep the receiving hopper of the crusher Full at all times so that the volume rate of rock entering any point in the crusher is greater than The rate of rock leaving, it is referred to as choke feeding. During choke feeding the crushing Action takes place between the jaw plates and particles as well as byinter-particle compression. Choke feeding necessarily producesmore fine sand require scareful feed control. For mineral liberation, choked feeding is desirable.

When installed above ground, the object of the crushing circuit is to crush the ore to Achieve the required size for down stream use.In some industries,for example, iron or eor coal, where a specific product size is required (ironore-30+6mm), careful choice of jaw settings and screen sizes are required to produce the minimum amount of fines(i.e.-6mm) and maximum the amount of lump ore within the specified size range. For hard mineral bearing rocks like gold or nickel ores where liberation of minerals from the host rock is the main objective, further stages of size reduction are required.