The production of raw materials for energy generation – coal, oil, and gas offers considerable scope for the use of decanter centrifuges, at least for coal and oil. The manufacture of gas is a little-used process now that natural gas is so freely available. When this phase passes, as gas availability reduces, then the gasification of coals and heavy oils will also offer good applications (as will the eventual need to convert coals into liquid fuels).
Decanter Centrifuges In Coal processing
In coal processing, the mined coal must be washed free of impurities. The run-of-mine coal contains the clay and rock that are within the coal seam, as well as roof and floor material. Coal itself is a relatively low-density material, compared with the impurities, and can be separated by sedimentation in a liquid of appropriate density.
An increasing proportion of the coal that is mined is crushed to a quite small particle size, partly to enable the removal of as much sulfur as possible. For such small sizes, the decanter centrifuge provides an excellent means of separation, also enabling the settlement fluid to be recycled.
Whatever the size of coal being processed, there will always be a need to separate residual coal from the washings, for which the decanter centrifuge is a standard separating device (as well as for the final dewatering of waste liquids the coal tailings). Fine coal may also be separated by means of froth flotation, and the dewatering of flotation concentrates is another good application for decanter centrifuges.
Decanter Centrifuges In Drilling Mud Processing
In the production of petroleum or natural gas from underground sources, the initial well holes must be drilled, often into very deep strata. The search for new oil resources also requires the drilling of many trial holes, more often dry than successful.
For such drilling, the drill head must be cooled and lubricated, and so a lubricating fluid (the “drilling mud”) is pumped down to the drill bit. Not only does the drilling mud cool and lubricate the bit, but it also carries the rock cuttings back to the surface, it prevents water leaking into the well from water-bearing rock, and it prevents the collapse of the hole behind the drill.
These duties require that the drilling mud be a complex liquid, basically a suspension of clay (bentonite) in water, but dosed with a range of special chemicals that allow it to cope with the range of rock compositions to be encountered, and to have the right density.
The preparation of a drilling mud is a size classification task, for which the decanter is very well suited. The used liquid is often too expensive to discard, so needs treatment for the removal of rock fragments for which duty, again, the decanter centrifuge is a very good choice.
For either of these duties, the decanter centrifuge will need to have full erosion protection by but can run at moderate or low speeds. It will also need an explosion proof motor (and back-drive equipment if this is used).