Vacuum Filtration: Available Equipment and Recent Innovations (005140f3-49f9-4218-ae53-265b4e8c850a)

In reviewing available vacuum filtration equipment in this paper, several types of filters have been included which are probably not familiar to operators in the mining industry. However, it was felt that these units might be of interest in the event that an application should arise for the filtration of a product in the future that does not exist today. In addition, exposure of our industry to equipment used in other industries might have a tendency to be thought provoking and perhaps lead to the development of equipment and/or applications in our industry which do not necessarily exist at this time. Most innovations in filtration equipment have been confined to the improvement or design change of components and accessories, particularly reflecting the availability of materials of construction that have been developed. Recent developments in the application of horizontal belt filters have been innovative. The application of this unit as a substitute for or an adjunct to thickeners in a CCD circuit can certainly be innovative and perhaps provide a basis for reduction in capital and operating costs in this area. For example, mill tails are generally pumped at the highest possible density that will adequately flow. Tailings ponds and dams with their attendant design requirements are based upon this estimated water volume. Availability of a much dryer, non-flowing filter cake opens up several new options for disposal. Considerable cost savings could result in the design and planning of disposal areas for containing dryer material. No attempt has been made in this paper to provide a manual for the operation of all of the many types of equipment that are available. Rather, the paper tries to present an overview. Fundamentals of Vacuum Filtration Filtration may be defined as the separation of solids from a liquid effected by passing the liquids through a porous medium. If the filtrate is induced to flow through the medium by hydrostatic head, we refer to it as gravity filtration. If we utilize super-atmospheric pressure upstream of the medium we call it pressure filtration and if sub-atmospheric pressure is applied downstream of the medium we call it vacuum filtration. Centrifugal filtration occurs when a centrifugal force is applied across the medium. Centrifuges will not be discussed in this paper. The process goal of filtration may be the production of dry solids where the cake is the valuable product, clarified liquid