Manufacturers of valves are often faced with the challenge of providing top quality products, to a variety of highly demanding industries in order to meet their ever expanding technical needs. This particularly applies when providing components in connection with the processing of materials designated as slurries.
There are several purposes associated with slurry valves. Within the applications provided by industries such a mining and minerals, these versatile components are called upon to control, divert, isolate and sample gases, liquids, powders and other forms of slurries. The valves are required to perform reliably and consistently in the most severe of conditions found in the mining and mineral processing industries. This will include valves capable of processing high pressure letdown to ’200 bar’, related to materials of high solid content, abrasive substances, corrosive chemicals or possibly a combination of them all.
Among the challenges a manufacturer of slurry valves must consider, are the oxidative leaching processes such as “HPLA”, or Activox for copper, nickel cobalt and gold, which extend any piece of equipment to the maximum limit. It is therefore necessary that specific and designed quality valves are available. However, the onus is on the user’s engineers, to ascertain the nature of the materials to be processed and provide the supplier with the information to enable the correct slurry valve to be provided.
In this respect, control, isolation, feed or drain valves will be customized to the specifications of the mineral ore process conditions and the piping or equipment needs. Manufacturers will provide the correctly designed valve, either for an “HPAL” process at 5,400 kPa, or for the “Avtivox” leaching process with a pressure of 1,000 kPa. The various applications in mineral processing where valves are required to operate under severe circumstances include; situations involving pipelines and autoclaves, in which feed and drain valves will be needed and the processing of ore and its isolation by slurry valves.
Any feed or drain valve situated within the immediate area of a flash tower or autoclave, must be designed to operate in severe conditions. These will include high temperature acid slurry and materials with a high solid content. General requirements for a valve in this environment will be a fast acting full bore flow and dead space free drainage. There must not be any leakage into the atmosphere and it is recommended that a fully hardened, diamond-polished piston is utilized to extend the packing life. Another essential advantage would be that of automatic crust breaking.
A slurry valve has the capacity of metering and dispensing quantities of thick liquids, or slurry at a fast rate of production. The slurry is allowed to flow freely by the valve, with the exception of a small interruption during the metering and dispensing cycle. In this instance, the heavier or more solid forms of the slurry do not have the tendency to level out or collect in the valve as easily as in normal conditions. The valve is of a basic construction and therefore easily maintained. It has a single moving part within the slurry, which initially rotates to close the valve in order to trap the slurry in an exactly ‘metered’ portion, from which it is then dispensed.
Originally posted 2011-10-19 07:58:15. Republished by Blog Post Promoter