The client sends a representative sample of his material or the components with its composition of the operational mill to enable LOESCHE for mixing all the components and execute a grinding test. 

The LOESCHE Grinding Test is made in a small LOESCHE mill (LM 3,6) where the geomet-rical construction corresponds with operational mills. 

 The material to be investigated is ground in the test mill under the same conditions that will exist later in the industrial mill. 

 The grinding test result obtained from the test is compared with that of a reference material with a grindability factor MF = 1. The product quantity between the tested material and the reference material is the grindability considering the fineness and moisture difference. 

 Unavoidable differences in the humidity of the feed stock or the fineness of the final product between the test and the later operational mill will be corrected by empirically de-termined factors. The resulting grindability factor MF is basing on standard conditions like 15 % R;0,09 mm and max. moisture difference of 6,0 wt% between feed and product. 

 The comparability study of the tested and standard material, produces the grindability factor. 
 

 The specific power consumption for grinding the sample will be measured at the shaft of the laboratory mill's gearbox and the taken electric power of the drive.  
  
Due to the fact that the laboratory mill will not operate under standard conditions which are mentioned above, like 15 % R 0,09 mm and moisture difference, this result has also be recalculated by empirically factors.  
  
In the test report specified power consumption is based on LOESCHE's standard conditions, and has to be translated to the operational mill. 
 
 

 Wear of the grinding parts occurs in every grinding machine. The extent of wear is de-pending upon the wear resistance of the material used for the components, the wearing properties of the grinding stock and the cause of wear produced (pressure, friction and abrasion wear). 

 The wear resistance of grinding component materials is known and will be considered on the basis of empirically determined factors. 

 Attention has to be paid to investigate the reason of wear (pressure, friction, abrasion or a combination). This wear will happen in the operational equipment as well as in the labo-ratory mill. 

 Additionally, the materials for grinding are composed of several constituents with varying grindability and varying wear tendencies. Very often, component which is the most diffi-cult to grind, is the one which causes the wear. In closed-circuit grinding installations op-erating with a classifier - practically all modern installations - the stock which is difficult to grind, concentrates in the grinding chamber and is subject to the grinding process until the point where it has reached the necessary fineness. Therefore, the material composi-tion inside the laboratory mill differs from that of the feed stock. 

 Due to this, the LOESCHE Wear Test is carried out in a small LOESCHE grinding instal-lation, equipped with a LOESCHE mill (LM 3,6) because the operational conditions can be simulated as near as possible for forecasting the operational plant. 

 The material to be wear tested in the test mill is ground for a predetermined operating time. The grinding parts of this mill incorporate a small steel plate which is arranged that its surface is proportionally representative for all the grinding parts. The loss of weight of the plate during the test is representative for all the grinding parts. Based upon the time of the test, the machine constants, the grindability factor and the specific wear, the life-time can be calculated for the operational LOESCHE mill. 
 

It is a known fact that quartz contributes considerably to wear in grinding equipment. On ac-count of its relative hardness and high compression strength, it has a very abrasive effect because the force required for grinding causes a high pressure on the grinding parts with consequent wear.  
This occurs when quartz has to be ground on account of its initial grain size. There is obviously no need to grind when the quartz has a smaller grain size than that required for the finished product because it comes less in contact with the grinding components. Due to the fact that the specific grinding force required for grinding the other material, as far as its constituents are concerned, is lower, the force with which the quartz contacts the other components is also lower. Therefore, it will cause hardly wear. 

This shows that the quartz content of a material sample alone gives only a small indication of the wear to be expected. The grain size of the available quartz is more important, including the grindability of the major component. 

In a grinding installation, operating in a closed system - practically all modern grinding installa-tions - the portions of the material which are difficult to grind, will concentrate in the grinding chamber. To reach the required degree of grinding, the grinding process is longer than that for the less difficult materials.  

Materials which are already fed to the grinding process in a sufficiently small size will behave in the same way as those which are easy to grind because, they require less grinding work. In this manner, quartz will concentrate or not concentrate in the grinding chamber during the process - depending upon the grain size of the feed stock grindability. 

In a grinding test, the quartz content of the meal will be compared with that of the material contained in the mill. If the mill content shows a higher content than the meal, the feed stock contains coarse quartz and wear has to be expected. If the quartz content in the mill is equal or lower than that of the meal, only a very low wear can be expected regardless of the amount of quartz. 

Due to this, the investigation of quartz in grinding test has be done and considered for stating the lifetime of grinding parts.