Solid material comminution or disintegration – Processes – With classifying or separating of material
Patent
1986-03-18
1987-07-21
Rosenbaum, Mark
Solid material comminution or disintegration
Processes
With classifying or separating of material
241 29, 241 81, B02C 2308
Patent
active
046812687
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method of comminuting lumps of homogenous and/or heterogenous mineral material in an autogenous primary grinding system, with the aid of screening, crushing and grinding apparatus, in which the lumps of mineral material are crushed to a given largest fragment size and then divided into a given coarse fraction, which forms the grinding mill charge of an autogenous primary grinding mill, and a given screened fragment size which is crushed to form a fine fraction.
The object of the present invention is to achieve maximum efficiency of comminution and minimum investment and operational costs in an integrated screeening, crushing and autogenous grinding system, in one or two stages. By mineral-material and material is meant here and in the following preferably ore minerals and industrial minerals.
2. Background Art
When processing a material, such as ore minerals and industrial minerals, in order to recover one or more of their valuable constituents, such as metal or industrial minerals, etc., the material is normally disintegrated mechanically in an initial sub-operation. The main object of this initial mechanical disintegration is to liberate the valuable constituents from the material prior to subjection it to a subsequent separation process, in which the valuable constituents contained in the material can be separated in dependence upon differences in colour, shape, and density, surface active properties, magnetic properties or other properties.
Normally, the material is primarily disintegrated mechanically to a certain extent when it is blasted from the rock or cleft face, and then subjected to a series of further comminuting operations, which may take different forms. In the past, further crushing of the of the material has normally been effected by crushing said material in a plurality of successive stages in jaw crushers and/or cone crushers, followed by fine grinding of the material in rotary drums containing grinding media such as balls or rods, normally made of steel. Because of the hardness of the rock, however, the grinding media are subjected to intense wear, with subsequent considerable costs.
In order to overcome this, there has been developed over the years a technique in which the material itself forms the grinding media, this technique being known as autogenous grinding.
The autogenous grinding technique has found wide use and is widely utilized the world over. Application of the autogenous grinding technique enables the extent to which the material is primarily crushed to be limited to a maximum lump size acceptable from the aspect of transportation. Consequently, the investment and operational costs of the crushers are relatively low. However, the absence of artificial grinding media having a high density in relation to the grinding mill charge, means that the specific grindability of the mill, expressed as grinding work/kWh energy consumed. Is decreased in comparison with commensurate mills in which grinding is effected with steel grinding media.
It is also known that the required power input of a drum mill when grinding, expressed in kW, is almost directly proportional to the density of the grinding mill charge media according to the relationship: .multidot.L.multidot.D.sup.2. 6, ##EQU1## L=mill length D=mill diameter
It is axiomatic of the two latter factors (L,D) that the dimensions of the mill will be increased when the required power input increases, because of the increase in energy consumption, as compared with the case when grinding with high densities grinding media; from which it will be seen that these factors increase the investment and operational costs of the autogenous grinding system.
In an autogenous grinding system, in which the grinding charge media is formed from the coarser and stronger parts of the actual material to be ground, the composition of the grinding charge formed is totally dependent on the properties of the material. Experience has shown that mineral deposits are seldom homogenous with respe
REFERENCES:
patent: 3773268 (1973-11-01), Bond
Borell Michael C.
Elmlid Carl-Gustaf
Marklund Olle E.
Marklund Ulf P.
Boliden Aktiebolag
Rosenbaum Mark
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