Maintenance of Flotation Machine

12.9.1 Maintenance Content

The main contents of flotation machine maintenance are: replacement of the impeller and cover plate (also called rotor and stator), adjustment and replacement of bearings, and replacement of the vertical shaft protective sleeve. In large and medium-sized flotation plants with many flotation machines, the division of maintenance work into minor, medium, and major repairs is clearly defined. Minor repair mainly involves checking the operation of the flotation machine, tightening or replacing relevant bolts, and inspecting and adjusting the bearing oil seal. Medium repair mainly involves replacing the impeller and cover plate, the vertical shaft protective sleeve, and relevant valves. Major repair mainly involves replacing all easily worn components, repairing the tank body, and replacing worn slurry pipes and valves.

12.9.2 Repair Methods

The repair methods are as follows:

(1) Impeller and cover plate. The impeller and cover plate are the core components of the flotation machine and are also easily worn parts. They affect the slurry aeration and agitation intensity during the flotation process. Due to wear and corrosion from long-term operation, they lose their production efficiency. At this point, the entire assembly of the impeller and vertical shaft is lifted out of the flotation machine tank, and a new pre-assembled assembly is installed. When replacing the worn impeller and cover plate, gaskets shall be used to adjust the axial clearance between the impeller and cover plate, keeping it within the specified range. At the same time, the concentricity of the impeller and cover plate shall be maintained to ensure uniform radial clearance around the entire circumference.

(2) Vertical shaft. Before installing the impeller, check whether the rubber hose protecting the vertical shaft is worn. If worn, a new rubber hose shall be replaced.

(3) Bearing clearance. When the axial clearance of the vertical shaft bearing becomes too large due to wear, it can be adjusted by tightening or loosening the inner and outer washers. If the oil seal on the lower cover of the bearing housing leaks, a new oil seal shall be replaced promptly, taking care not to compress it too tightly.

(4) Tank body and tank liner. During long-term operation of the flotation machine, strong agitation of the slurry causes wear and corrosion. The tank liner may become deformed and worn, and the tank body may become thinner, leak, or develop holes. In such cases, repair welding shall be carried out promptly. If the damage is severe, the entire tank body or liner shall be replaced.