Multotec has just commissioned a second cylindrical welding machine (CWM) for producing wedgewire cylinders for cylindrical interstage screens. Based on its pioneering original unit developed several years ago, the new CWM is capable of producing seamless wedgewire cylinders of 1.9 m in diameter and up to 3 m long. This diameter is believed to be the largest of its kind available worldwide. Multotec worked with German partner Steinhaus some eight years ago to develop the original machine to produce wedgewire cylinders for the coal, gold, diamond and brewery sectors, but specifically with a view to producing robust, long life wedgewire cylinders for interstage screening applications in carbon-in-leach (CIL) and carbon-in-pulp (CIP) processes in the gold industry.Multotec’s Derrick Alston says the new machine, which is already in operation alongside the existing CWM, effectively doubles production capacity and reduces lead times, and is expected to meet market demand for the next decade. About 40% of the company’s wedgewire cylinders are produced for the export market.
The existing CWM produces wedgewire cylinders with a maximum diameter of 1.7 m and a length up to 6 m.
“Multotec has supplied wedgewire to the industry for more than three decades and we have steadily evolved to become the most reliable supplier on the market,” he says. “In carbon recovery applications, wedgewire cylinders go to the heart of the process and are therefore of a critical nature. Prompted by increasing market demand and driven by the objective of giving our customers confidence in an uninterrupted and reliable supply of these cylinders, towards the end of 2009 our shareholders gave the go ahead to make a significant investment in developing a second CWM, which has now been commissioned.”
“One of our foremost users is Kemix who, in conjunction with Anglo American, some years ago developed an innovative technology for interstage screening in the gold extraction process. Used in CIL or CIP applications to separate activated carbon from pulp, its Mineral Processing Separating and Mineral Processing Separating Pumping screens are today considered the benchmark in interstage screening.”
Multotec wedgewire cylinders are unique on the global market in that they are produced without joins using a cylindrical welding process, and can be produced to size to suit specific customer applications. Apertures down to 200 micron are produced using a variety of wedgewire profiles and materials. Multotec’s specially developed CIP profile is designed for the gold mining industry and has a high release angle to reduce blinding and an improved open area to increase throughput. The 28 SB profile, also used in the gold mining industry, can provide even longer life. 304 stainless steel is used for applications subject to corrosion, while 430 stainless steel is used in areas that require abrasion resistance properties only. Wedgewire cylinders are manufactured for all types of mechanically and air swept cylindrical interstage screens.
Alston says the accuracy of the aperture is essential to the efficiency of the process and the new Multotec CWM features enhanced capabilities to ensure this, including a modified welding head that applies a more consistent welding pressure to the weld, resulting in a consistent and repeatable quality. All standard aperture sizes are available, dictated by the carbon or resin size range, and both CWMs are able to manufacture any intermediate aperture size required by customers. Advanced measurement and control instrumentation allows close tolerances on apertures to be achieved.