Monthly Archives: January 2020

How to Use Slurry Pumps

The slurry pump is a heavier and stronger version of a centrifugal pump used to handle harsh or abrasive applications. Standard centrifugal pumps are used mainly to dissipate clear liquids, while slurry pumps are used for hydraulic solids transportation.

The term “Slurry Pump” refers to all of the devices used in the transport of solids. More specific names are given to them based on the size of the solid being transported or based upon its particular use.

The slurry pump is used to transport mud, clay, silt and sand in the size range of solids up to 2 millimeters. Sand and gravel pumps handle the transporting of shingle and gravel in the 2 to 8 millimeter range. Additionally, gravel pumps may transport solids up to 50 millimeters in size. Dredge pumps are used to handle solids up to and exceeding 50 millimeters.

Specific names are also based on the application or use. Froth pumps handle frothy slurries, mainly in flotation. Carbon transfer pumps provide the gentle hydraulic transportation of carbon in pulp and carbon in leach circuits. Sump pumps are mainly operating pumps from floor sumps that have submerged houses but dry bearings and drives. Submersible pumps, like the name implies, are fully submersed, including the housing and drive.

Depending upon the application, the slurry pump can be installed dry, semi-dry, or wet. Most horizontal slurry pumps are installed dry. In this case, the bearings and the drive are kept out of the slurry, and the wet end is closed. The slurry is free standing and clear of any of the liquids. The vertical tank may also be installed dry. This has an open sump with the pump casing mounted directly under the tank. The slurry is fed from the tank and expelled horizontally. No submerged bearings are required in this design.

Semi-dry installation is a special configuration for dredging operations. Horizontal pumps are used with wet ends and submerged pads. For this application, special sealing considerations must be made for flooded bearings. Wet installations are used when there is a need for a pump that is completely submerged. An example is removing slurry from a tub where there is a very volatile level of free slurry. In wet installations, both housing and drive are flooded, which require special design and sealing considerations.

When determining slurry pump design, the type of application is considered to ensure proper performance under a variety of conditions. They are designed to handle highly abrasive, abrasive, and mildly abrasive conditions.

Slurry Pump Seal Installation

As far as we know, there are many types of sealing for mud pumps. But it is difficult to judge which is better. All types of sealing have their strengths and weaknesses. Here in this section three main types of sealing will be introduced.

First is the packing seal. This is the most common seal. The sealing function is completed by injecting pressurized water into the filling material. Through this method, the pump body can prevent pulp leak. For multi-stage pumps in series, they will adopt a packing seal. This packing seal is very simple in structure, easy to maintain and cheap in price.

The next type is impeller seal. It can prevent the leakage of the slurry through the acting force of an impeller which is opposite to the centrifugal force. When the positive pressure in the pump inlet is not higher than 10% of the pressure in the pump outlet, the first pump of the single-stage pump or multi-stage pump in series can adopt this seal. There is no need to use the seal water and to dilute the slurry. Besides, the sealing effect is quite good. Therefore, when the slurry is not allowed to be diluted, it is worth considering this seal.

The third type is machinery seal. Generally speaking, this seal is commonly used in the situations with high requirements, such as chemical industry, food industry. However, this mechanical seal is not perfect, because it is hard to repair and also its cost is quite high.

Since there are so many sealing types, their installations are also different. The following passage will take the machinery seal’s installation in the slurry pump for example. There are a lot of things that should be done when people set up the machinery seal in the slurry pump. Firstly, check the model number and specification of the Machinery Seal.

Secondly, check whether the size accuracy, geometric accuracy and mutual relation of the installation position are in accordance with the technical requirements. They include the following aspects, such as radial runout allowance, the degree of smoothness of the axis, displacement of axial direction and so on.

Thirdly, when people set up the machinery seal, they should keep clear and do not allow the tool to beat the seal element. Or else, the element will be destroyed and broke.

Fourthly, remember to coat a layer of clear motor oil and turbine oil in the surface of the dynamic ring and stator ring during the installation.

Fifthly, ensure the head face of the stator ring and center line of the end cover to be vertical. Last but not least, in order to ensure the work length people should screw the pinching screw up tightly.