Mining is a complicated and challenging field for people as well as for equipment. In the mining industry, the primary goal is to extract minerals and nonrenewable resources from the depths of Earth. Hence, there is continuous innovation in techniques and tools of mining due to the rising demand for better operational efficiency. However, this sector heavily relies on valves to assist in various critical operations. But such valves need to be extremely durable and heavy-duty as the conditions can be harsh and the product highly abrasive. Many successful companies offer reliable valve solutions for mining industries around the world.
There is a long list of valves that are used in the mining industry, such as:
- Knife gate valve
- Ball valve
- Pinch valve
- Butterfly valve
- Check valve
- Slurry valve
- Air release valve, etc
Some of the types are discussed in this article.
1. Knife gate valve
Knife gate valves are made to function in some extreme environments. They are designed mainly to control the flow of fluids with high content of suspended solids. Because they consist of a sharpened blade to cut through heavy fluids. In mining industries, knife gate valves are incredibly beneficial for handling corrosive, viscous, and abrasive media, including grease, oils, slurry and wastewater. These valves are easy to actuate and offer minimum pressure drop in the completely open position. Furthermore, knife gate valves are lightweight and a very cost-effective.
Typically, the knife gate valve does not need maintenance or replacement because it has an acid-proof stainless steel knife, which is less susceptible to damages caused by corrosion. They offer only on-off services, which means the valve will be either completely opened or completely closed. It is recommended not to utilize them for regulating the flow. Because whenever fluid is forced against a partially closed gate, vibration occurs, and cavitation can damage the seat and body. In addition, these valves are created to open and close slowly to safeguard against the water hammer.
2. Ball valve
A ball valve is a member of the family of quarter-turn valves. It was developed exclusively for mining applications. Furthermore, it possesses a spherical obturator with a cylindrical hole, normally of the same diameter as the pipe. This hole is responsible for controlling the flow of fluid in a system. When the hole aligns with the flow direction, it allows fluids to flow through. Alternatively, the flow is shut off completely when the ball is rotated 90 degrees. In both cases, the outer handle or lever of the valve acts as an indicator of the valve’s status. The valve is open if the handle is parallel to it, and it is closed when the handle is perpendicular.
The ball valve is an extremely robust and highly durable valve that serves a simple on/off action. Plus, these valves have high-quality components for reliable operation in copper, silver, gold and other mining applications that demand premium performance. The ball valve is available in different designs, sizes, and materials. Moreover, it comes in one-piece, two-piece or three-piece designs. It is built tough to maintain its performance after many cycles. However, it lacks the throttling action that many other valves offer.
3. Pinch valve
A pinch valve is an on/off valve that is used to start, stop, or regulate any fluid flow. This valve has been successful in mining and underground construction operations for many years. Typically, it is used for mined raw materials, which include minerals, ores and coal. As well as, it also has applications in the removal of waste products that are extracted during the mining of raw materials. Pinch valves are robust and abrasion-resistant because the fluids they handle can sometimes be very abrasive and harsh.
The pinch valve can be operated either manually or pneumatically. This valve can withstand higher pressure and temperature; that’s why it is ideal for mining and mineral industries. It consists of three parts: body, internal rubber sleeve, and end connections. The corrosion-resistant rubber sleeve is the component that handles the flow of media. Moreover, the pinch valve does not possess any additional parts that will require frequent replacing, such as rings, seals, packing, etc. Hence, it is compact, lightweight and requires little to no maintenance.
4. Butterfly valves
The butterfly valve is a quarter-turn valve used to stop, regulate, and start media flow. It controls many crucial operations in mining industries, especially slurry transport, dewatering and isolation. Besides these, it can be used across a wide range of applications in different industries. A disc is mounted on a rotating shaft; it is equivalent to a gate in a gate valve or a plug in a plug valve. When the valve is closed, it completely blocks the line; in contrast, when it is totally opened, the disc is at a right angle to the flow of media.
Butterfly valves are easy and fast to actuate; a 90° rotation of the lever provides a complete closure or opening of the valve. Moreover, these valves are relatively inexpensive to build, require less material due to their design. They have a compact design, which means they require considerably less space compared to other valves. Another reason for butterfly valves popularity is their reliability and reduced maintenance requirements.
5. Check valve
The check valve is a non-return valve or one-way that is quite common in every industry. It is a simple tool, which prevents damage and ensures efficient functions by prohibiting the backflow of fluids. In the mining industry, a high-quality check valve is installed to minimise the risk of equipment damage, replacements, breakdowns, and, resultantly, unscheduled downtime. Moreover, check valves are placed in series to stop the reverse flow and prevent damage to the machine during the discharge operation. Additionally, check valves support mine dewatering operations, which decreases the water table near extraction sites and mines. Besides, it is used throughout the piping network, transferring water to and from mine sites.
These valves come in different materials, designs, and sizes. Unlike other valves, it has automatic operation, and no labour is required to open and close it. Check valve work on pressure differential principle and features a single inlet and outlet. To put it simply, it will open only when the upstream pressure is higher than the downstream pressure. Alternatively, it will shut off as soon as downstream pressure rises above the upstream pressure. Such pressure is termed the cracking pressure and is one of the key features present in all check valves.