Non-Metallic Centrifugal Pump Solution for Filter Press Intake
Centrifugal Pumps for filter press intake in mining industries can wear-off quickly. Though material and hydraulic selection of pumps are often assessed extensively, pump operation and integration into the filter press cycle are not.
In an actual case MUNSCH Engineers introduced the pump’s point of view to a filter press routine and achieved significant results with reasonable effort.
The refining of precious metals from ore or recycling material often creates fluids with high acid and solid content. Non-metallic or lined equipment is to be found everywhere in these processes, pumps from various thermoplastic materials among them. In a recent case, one of the world leading companies in the precious metal business sought for an optimization of their filter press intake pumps as the existing pumps were being sent to maintenance every three weeks, often with major damage and wear (Fig. 1). These pumps were supposed to feed a leaching mixture of hot hydrochloric acid containing a reasonable amount of suspended cobalt chloride into a filter press.
A team of operators and MUNSCH engineers analyzed the intake cycle and visualized it from a pump’s point of view by means of a Q-H diagram (Fig. 2). It was obvious the pumps were extremely outrunning their limits, a mode of operation known for its strong impact on wear.
Given the actual fluid composition, alternative materials were not an option. Thus, the MUNSCH team focused on the optimization of the intake cycle. A constant by-pass was installed to prevent the pumps from underriding the minimum flow limit towards the end of the intake cycle. In addition the team used the existing pressure measurement and a variable frequency drive to install a control loop in which the pressure set the pump’s speed to predefined values (Fig. 3). Henceforth operators were able to run the pumps within reasonable and less abrasive limits from start to end. A MUNSCH pump with special hydraulic design for abrasive fluids was installed and multiannual life times were achieved.