Gold leaching plants use valves for numerous flow control and isolation services. Valve performance affects the whole leaching process, so it is vital to select the right type of valve for the right application.
Requirements for tightness, abrasion and erosion resistance, and pressure range, are among the key variables when choosing the optimal valves. Reliability should also be considered, since malfunctions may lead to safety risks and added process downtime.
Valves for thickening
Thickeners increase the content of solids and thus the gold concentration of the slurry. Unwanted gangue is separated in the thickener and processed in the tailings stream. Process water, on the other hand, is recycled back for upstream processing.
Valve installations in thickeners are required for overflow as well as underflow service. On the overflow side, butterfly valves provide effective flow control. Knife gate valves are also used. For the thickener underflow, pinch and knife gate valves are the most common solutions.
Valves for pressure oxidation
If the gold ore is refractory by nature, it may require pre-treatment processing before leaching.
One pre-treatment option is pressure oxidation (POX). Due to the conditions that valves are subjected to in the POX process, the highest possible resistance against corrosion, erosion, and deterioration caused by solids is required.
To maintain the sealing abilities of slurry feed valves, the right material, seat and coating choices play an important role. Metso offers the most competitive valve solutions for the POX process.
Valves for leaching tanks
Regardless of the leaching method (CIL, CIP or CIC), valves must provide reliable control for the liquid, gaseous and air flows.
The presence of cyanide creates challenges for process control and makes the correct valve material selection essential. When performance requirements are a high priority, process ball valves are a good option for the leaching tanks.
With the right material, coating and seat selection, ball valves provide a long service life and precise flow control capabilities.