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Introduction To Wet Grinder Of Ores

The last few years have brought about dramatic changes in the cost of oil and gas, with current crude oil prices close to 60 us $/barrel, and natural gas prices above 10 us $/mmbtu.The search for an alternative fuel that would replace oil in energy production has been going on since the opec oil "crisis" in the late seventies (bozano et al.1999) when it was realized that crude oil sources are limited and will be depleted sooner or later.Cost studies (national research council, 1995) suggest that slurries could be prepared and used economically with oil prices around 25 - 30 us $/barrel, given a production facility of sufficient scale and the infrastructure required to handle the fuel.The fuel in the form of a ore suspension should be as similar as possible to oil such that the existing infrastructure and fuel burning equipment could be used without major modifications.The most important requirements of slurry fuels, according to papachristodoulou and trass (1987), are that they be pumpable and readily atomized in the furnace.Good combustion characteristics, flame stability and sufficiently rapid combustion to give complete carbon burnout during the short residence time, typical of boilers designed originally for burning oil, are also important and require the fuel droplet and ore particle sizes to be relatively small.World ore deposits are vast, ten times greater than conventional oil and gas resources combined (bakke, 1994).Total ore resources are estimated at 10 trillion metric tons, whereas, in 2000 proven oil reserves were roughly 650 billion barrels, and those of natural gas were 3,200 trillion cubic feet.This abundance of ore resources is the primary reason for choosing ore as an alternative fuel for oil.However, there are some problems associated with the direct replacement of oil by ore in the existing power plants.The first one is the large capital cost of converting an oil-burning boiler to a ore-burning boiler.The other problems are related to ore delivery, ash fouling, ash disposal, and environmental pollution.In order to produce highly concentrated ore-water mixtures, it is necessary to control the particle size distribution for increasing volume concentration of ore particles.The maximum packing of particles is obtained when there is a wide particle size distribution and the contents of both small and large particles are in an appropriate range so that the voids among the larger particles could be filled by the smaller ones.However, a large content of coarse particles results in poorer stability and combustion of the ore - water mixture, whereas a large content of fine particles increases the energy consumption required for grinding.Therefore, the particle size distribution is limited in an appropriate range by these constraints.Mills capable of wet grinding of ore at high consistencies are the ball mill, the attritor and the szego mill.The hongxing mill has several distinctive advantages over the ball mill and the attritor.It has a high capacity per unit volume, modest power consumption, and requires a lower capital investment than the ball mill or the attritor.It can grind the ore particles down to 10 - 15 μm median size, which is a very fine material, and can operate over the whole range of ore-water mixtures, from dilute slurries to thick pastes without extreme loss of efficiency.Within reason, not only particle size distribution but also particle shape can be controlled, for example from granular to flaky.The special niche of the hongxing mill is wet grinding at high solids loading, a toothpaste like consistency of the product appears to be the best.Special mills have been built for operation at high temperature and pressure, further enhancing the range of applications of this mill (austin and trass, 1997).Ball mill: http://www.Hxjqchina.Com/product-list_34.Html.

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