Modern Mining July 2019

PRODUCT News

Understanding design choices for vibrating screens

It is important not to generalise about the advantages and disadvantages of differ- ent vibrating screen technologies, advises Kwatani CEO Kim Schoepflin; the key con- sideration is the application. “When a customer considers their options for a screening machine, there are a number of good technologies fromwhich to choose,” Schoepflin says. “The appropri- ate technology choice will depend on the application, and we believe there is a space for every technology.” Brute force screening is the most com- mon technology employed among mining screens. Its benefits include being gener- ally cost effective, relatively simple to

maintain and economic in terms of life cycle costs, all of which translate into lower Total Cost of Ownership (TCO). “Having the mechanical and metallur- gical knowledge in-house, Kwatani can provide the technology that best suits the application,” she says. “We are not tied to one technology, and our primary focus is on understanding exactly what the cus- tomer needs, and providing a solution that is engineered for tonnage.” Twin-mass or resonant screens, which run very close to a natural frequency, have a self-amplification benefit, says Kenny Mayhew-Ridgers, Kwatani’s Chief Operating Officer. “This gives the screen a greater energy- efficiency,” he says. “There are, however, limits on the size of these units. In addition, maintenance is more costly as springs or rubbers must be changed regularly or the efficiency benefit is lost.” He notes that twin-mass screens also tend to be heavier. This can cause con- fusion when presenting technology comparisons to customers. “Often the overall mass of the twin- mass screen is compared with the mass of the brute force screen, and this is obviously not correct,” he says. “Rather, it is the deck sizes that must be compared, as this is the element that does the work.”

in the wastewater treatment sector. “Quax is well proven in Europe. It is a reli- able workhorse that can pump in all sorts of conditions. Apart fromdealing with large particles and sludge, the pumps work par- ticularly well where suction lift can be an issue,”Vine says. All units are equipped with a run-dry capability which is considered essential in dewatering applications. The pumps are simple to install and operate, and offer reliable pumping even under challenging conditions. This, Vine says, enables end- users to dewater effectively in areas that are traditionally difficult to reach. The pumps are equipped with a range of impeller options, increasing the versatility of these units. These include a two bladed impeller for dealing with large particles, a screw impeller for pumping in thick sludge, a stainless steel impeller for applications with a low pH and a high head impeller. Integrated Pump Rental, website: www.pumprental.co.za Schoepflin highlights that Kwatani works to raise awareness in the industry about what each technology is about. This makes it easier for users to make informed decisions about the technologies they choose. She also says it is important for users to be confident that their chosen screen is well supported by local experts. “It is vital for OEMs to prioritise the cus- tomer’s application when considering the basic screen technology and design,” she concludes. “While optimising screen pan- els to achieve higher screening efficiency is always an option, it is not the silver bullet.” Kwatani, website: www.kwatani.co.za While the mechanics that drive the screening process are different, the motion of the panel is what is important. This is where interaction occurs between the particles and the screen panels. The efficiency of the process then depends on the screen’s speed, frequency, drive angle and movement of the panel relative to the particles. While some proponents will generalise about common challenges with brute force screens, Mayhew-Ridgers notes that these observations are seldom valid. Various manufacturers offer a range of brute force technology solutions, each with its own benefits.

A large Kwatani triple deck screen for a diamond mine under scrutiny by the company’s engineers.

Hydraulically driven pumps added to rental fleet No two pump rental applications are alike, and it is this understanding that has posi- tioned Integrated Pump Rental as one of the leading pump rental operations in South Africa.

plug-and-play operations where access to electric power is not an issue, but others, especially in remote or difficult to reach areas, require the use of diesel-driven pump sets.“Large diesel-driven pump sets are not always the answer where electricity is not available and to provide customers with an

Managing Director Lee Vine says that some dewatering applications are simple

effective solution we recently intro- duced the Quax hydraulically driven pump range into our fleet.” Not only will these pumps com- plement the existing Integrated Pump Rental fleet by filling the gap between the electrically operated submersibles and those powered by diesel but they will also open opportunities for the company to extend its reach into other markets. Vine says these include dewatering on construction and infrastructure projects in built-up areas as well as

Lee Vine, MD of Integrated Pump Rental, flanks Quax hydraulically driven submersible pump systems.

42  MODERN MINING  July 2019