Ore crushing plant is used for crushing and grinding ores in order to get size reduction. This crushing plant mainly includes crushing, grinding and screening. It can be replaced the first three stages of ore processing or ore dressing.
Ore means that a mineral or an aggregate of minerals from which a valuable constituent, especially a metal, can be profitably mined or extracted. An ore is a material that contains a metal in such quantities that it can be mined and worked commercially to extract that metal. The metal is usually contained in chemical combination with some other element in addition to various impurities.
Ore mineral can be classified in different contents as follows.
1. By ore minerals are useful in industrial performance ore can be divided into metal ores (such as iron ore, copper ore, molybdenum ore, bauxite ore, platinum ore, zinc ore, cobalt ore, silver ore, gold ore, nickel ore, titanium ore, tungsten ore, platinum ore, tin ore, uranium ore, etc.) and non-metallic minerals (e.g. fluorite ore, asbestos ore, lead ore, etc.).
2. By ore useful minerals or metals contained in the number of elements ore can be divided into simple minerals (such as tungsten ores, mercury ores, etc.) and integrated mineral (such as Pb-Zn, W-Sn ore, etc.)
3. By mineral content of the useful components it can be divided into poor ores (such as poor banded magnetite ore, iron 30%) and rich ores (compact massive magnetite ores, iron 60%).
4. According to the structure of ore it can be divided into dense massive ore, disseminated ore, banded ore, breccias ore, etc.
5. By mineral weathering it can be divided into different levels of primary ore, oxide ore and mixed ore.
Ore crushing plant working process
Generally, the whole ore production line consists of jaw crusher, ball mill, classifier, magnetic separator, flotation machines, thickener, dryers and other major equipment, with feeder, bucket elevator and conveyor can be composed of a complete ore production line. This production line feature with high efficiency, low energy, high capacity, economical and so on.
Big ores are fed to the jaw crusher evenly and gradually by vibrating feeder through a hopper for primary crushing. After first crush, the material will transferred to other crusher by belt conveyor for secondary crush; the crushed materials will then transferred to vibrating screen for separating. Then, the materials will be transferred into the ball mill evenly for ore grinding.
After ball mill grinding, the ore fine material into the next process: classification. Because of the weight of solid particles is different, the speed of precipitate in liquid is different, according to this principle, spiral classifier can washed and classified the mixture ore. After classifying, ore particles are sent to flotation machines, depending on the mineral characteristics with different chemicals, making the needed ores and other materials to be separated.
Selection of ore crushers in ore crushing plant
Knowing the number of crushing stages we can now start to select the correct crusher for each reduction stage. Depending on operating conditions, feed size, capacity, hardness etc, there are always some options.
1. Primary ore crusher
For soft feed (below Mohs5) a horizontal shaft impactor(HSI) is normally the first option if capacity is not too high. For harder feed there is a choice between a gyratory crusher also named cone crusher or a jaw crusher.
Rule 1: Always use a jaw crusher if you can, being the most cost effective alternative.
Rule 2: For low capacity use jaw crusher and hydraulic hammer for oversize
Rule 3: For high capacities use jaw crusher with big intake opening
Rule 4: For very high capacities use gyratory crusher also named cone crusher.
2. Secondary ore crusher
In a rock crushing circuit, the second stage normally starts to be of importance for control of size and shape. Because of this the jaw crusher, in most cases, is disqualified as secondary crusher. Instead the cone crusher is used more frequently. Also in comminution (crushing and grinding) circuits for ore and minerals the cone crusher is frequently used as the secondary stage.
Compared to other crushers the cone crusher has some advantages making them very suitable for size reduction and shaping downstream a crushing circuit. Reason is the crushing chamber and the possibilities to change feed and discharge openings during operation.
3. Final crusher or tertiary crusher
For many rock and gravel crushing circuits the final crushing stage is of special interest. The final sizing and shaping will take place in this stage influencing the value of the final product. For hard rock circuits there are only two options, cone crushers or vertical shaft impact crusher (VSI).