We continue to consider the main stages of industrial tests. In this article, we consider the next stage in full-scale industrial tests conducting — the testing method determination.
Two methods (variants) use for industrial tests conducting in practice:
- tests providing with a new grinding balls;
- tests conduction by the replacing grinding balls method.
The first test method implies the new grinding balls loaded in empty test mill. As a rule, this is assembly of grinding balls. The assembly average diameter should be equal to the grinding balls average diameter in the operating mill (prior to the spent grinding balls unloading). We indicated two ways for determination the average diameter of grinding balls in a mill at our previous articles (The grinding balls bulk weight in mill without unloading grinding media and The grinding balls bulk weight in fully unloaded mill) . This method use when the mill put into operation after major repairs. This method advantages:
- there is 100% guarantee, all mill performance refers to the testing grinding balls during industrial test;
- the shorter testing period;
- there is no need to purchase additional grinding balls volume.
The second testing type used when there is no possibility to overload mill with grinding balls or there are no planned mills repairs. This method particularity is needs to accurately calculate replacement time the previously used grinding balls for the new ones. As a rule, this period is from two to three months. The replacement period calculation based on average value of the daily loading norm the mill by grinding balls. For example, a mill has 130 tons of grinding balls and the loading norm is 1 ton per day (with observance the planned capacity), then it replacement period will be at least 130 days. It is very important to track the previously used grinding balls in the mill during grinding balls measurements in the mill. Their presence evaluate visually or by selecting samples for chemical analysis. We draw attention to the fact, the grinding balls specific consumption may increase during the replacement period. This is due to the test harder grinding balls will rub the previously used softer balls.
It should be noted, the testing period should be between three and six months (without the replacement period account or grinding balls adaptation in mill), regardless the test method chosen. The mill should operate in normal mode without any changes in technology during all this period.