he amount of froth scraping is an important aspect flotation machine operating，which is directly related to the quantity and quality of flotation technology.

the amount of froth scraping not only depends on the thickness of foam layer ，but also is related to the balance and stability of flotation technology. In order to get qualified concentrade and fully recycle metal，it is believed that sweeping is neessary process.

It seems that increasing the scrapped amount of froth may impove the recycling ratio. However, the fact is flotation effenciency will become even worse while the scrapped amount of froth gradually increase, lots of gangues are easily scrapped into the end-products. That will lower the quality of foam and meanwhile heighten the recycling amount of medium ore,which break the balence of flotation process.

In the process of flotation, the pulp surface will be adjusted by the the pulp gate of flotation machine in order to conmtrol the thickness and of froth layer and the scrapped amount of froth.And operator will adjust properly and make it as the emergency method to deal with the all kinds of rapid changes.However, adjusting pulp gate can't eliminate the factors to cause all kinds of rapid changes.

During operation, non-guidance frequent adjustment will affect the stability of flotation process. In fact，there are many factors to affect a froth scrapped amount.If the reason is change in pulp concentration and fineness, you should immediately make connection to the grinding and classifying operator. If the reason is the improper amount of the chemicals, we should increase or decrease the amount.Only when the situations such as pulp overflow or a sharp decline of pulp surface so that flotation process has been affected directly, to use pulp gate to make an immediate adjustment will be thought to be necessary.