In the mining industry, one of the pumps frequently used in mines is the slurry pump. This is a type of pump capable of transporting solid-liquid mixtures and is an indispensable important pump type for conveying various slurry media containing a large amount of particles in mines. In this article, Changsha Zoomlian Pump Industry, a slurry pump manufacturer, will introduce how to select a slurry pump for mines, allowing you to have a better understanding of the selection of slurry pumps for mines.
I. Calculation of Key Hydraulic Parameters
Flow rate (Q) and head (H)
(1) Flow rate: The pump type should be selected based on the process flow rate (maximum/average/minimum), and the high-efficiency range of the pump characteristic curve should be verified (typically 70% to 120% of the rated flow rate).
(2) Head: The total head must cover the pipeline loss (Darcy formula) + vertical height difference + outlet pressure requirement, with an additional 5% to 10% margin. The friction resistance of high-concentration (>60%) pulp needs to be corrected separately (multiplied by a factor of 1.1 to 1.3).
2. Net Positive Suction Head (NPSH)
The available net positive suction head (NPSHa) must be greater than the required net positive suction head (NPSHr) of the pump. When the pulp temperature is above 50℃ or the altitude is above 2000m, the NPSH value needs to be recalculated to prevent cavitation damage.
II. Technical Requirements for Selection Based on Medium Properties
1. Particle Characteristics
(1) Particle size distribution:
The maximum particle size (dmax) must be less than one-third of the minimum flow passage of the pump's flow-through components (for example, the width of the impeller flow passage ≥ 3dmax).
The shape of the particles (angular/circular) affects the wear rate. For angular particles, materials with higher hardness (such as Cr28 alloy) should be selected.
(2) Concentration (Cw):
When the mass concentration is greater than 65%, the pump speed should be reduced (it is recommended to be no more than 800 rpm) to prevent the deterioration of the medium's fluidity.
When the volume concentration is greater than 35%, the head needs to be corrected (H slurry = H water × ρ slurry / ρ water).
2. Density and Viscosity
When the pulp density is greater than 1.5 t/m³, it is necessary to verify whether the shaft power (P = Q × H × ρ / (367 × η)) exceeds the rated value of the motor.
When the viscosity is greater than 200 mPa·s (such as clay-containing slurry), wide-flow-channel impellers (such as semi-open impellers) should be selected to prevent clogging.
3. Corrosiveness
When the pH is less than 4 or greater than 10, corrosion-resistant materials (such as natural rubber which is resistant to pH 3 to 11 and EPDM rubber which is resistant to pH 1 to 13) should be selected.
(2) For acidic pulp containing Cl⁻ or SO₄²⁻, ceramic or ultra-high molecular weight polyethylene (UHMWPE) materials should be used.
III. Pump Type Structure and Material Matching Technology
Impeller design
Closed impeller: High efficiency (η ≈ 75% - 85%), suitable for low concentration (Cw < 40%) and small particle (dmax < 3mm) conditions.
(2) Semi-open impeller: It has strong anti-clogging performance and can pass particles up to 8mm, but the efficiency is reduced by approximately 5% to 10%.
(3) Fully open impeller: It is used for the demand of heavy medium with large and numerous solid particle diameters.