The large quantities of low grade iron ore around the world are forcing the industry to upgrade for the steel producers. This requires more benefication and there is a tendency towards finer grinding. Thus reliable dewatering solutions are demanded, but at the same time they should require low capital investment as well as low operation cost, Outotec points out.
Demand for iron ore has increased dramatically in the last years and is forecast to remain at stable high production levels for years to come. It is expected that the world economy is facing a stable continuous growth of iron ore to 2,000 Mt and more over the next decades. Furthermore it is expected that the existing and known high grade ore resources will decline, and the iron ore industry will be forced to implement more and more advanced beneficiation plants. As a consequence of the more complex benefication requirements, there will be a need for modern solutions for iron ore dewatering that are reliable mechanically as well as cost effective and with high capacity per unit at the same time.
From the CAPEX point of view, the ranking between pressure filtration and vacuum filtration is clearly in favour of vacuum filtration. Only for finer and highly contaminated products do the product recoveries of pressure filters justify the higher investment costs.
With respect to vacuum filtration technology, a distinction between horizontal and vertical vacuum filtration equipment can be made. Vacuum belt filters like RB-SV should be considered for heavy material in the coarser grinding range. In the wide range between heavy coarse and very fine material, use of Ceramec and RVDF technologies predominate.
In addition to the well known and commonly used vacuum disc filters, a reliable and low operating cost filtration solution with a large filtration area for high capacity and stable product moisture content has been developed and will be steadily improved according to process demands. This filter is called the Outotec Larox CC, Ceramec capillary action filter, which guarantees stable capacity and good moisture results with low capital investment and operation costs and easy maintenance and monitoring.
The Larox CC filter also has other remarkable advantages, because it is a plug and produce solution including features such as a small installed vacuum pump, easy online monitoring and continuous steady product characteristics. The automation features of this technology allow completely independent cake forming and drying control. The low vacuum pump requirements reduce the investment costs, because all the required features are mounted on the filter rig itself and no additional cabling work and transformers are needed.
The effective and reliable construction enables easy maintenance and provides the lowest operating costs, because no cloth changing is needed and the ceramic plates last for years. Conventional vacuum filtration methods have been the most prevalent in fine iron ore dewatering. Product quality needs, lower ore grades, complex mineralogy and energy costs have resulted in iron ore producers seeking better solutions for dewatering, in particular pelletizing feed. New advanced filtration methods have been introduced to the market.
A paper Experiences with modern dewatering technologies in Fine Iron Ore application describes how these modern methods are answering the needs of the industry. Performance of advanced dewatering technologies (pressure filtration and ceramic capillary action filtration) for iron ore applications have been studied, and the findings are based on both industrial and pilot scale experiences on different materials. For example, the results show that the cake moisture content of iron ore pelletising feed can be optimised more effectively by using modern filtration technologies. By selecting the most suitable and adjustable equipment, the effects of variations of feed material on down stream processes can be minimised and the possibilities of processing more difficult raw materials to high quality pellets are better.
Outotec innovates, develops and delivers sustainable technology and service solutions to minerals, metals, chemical and energy industries. Outotec collaborates lifelong with its customers in order to optimize the utilization of raw materials and energy efficiency as well as to minimize the environmental impact and operating costs. Outotec develops, designs and manufactures industrial Larox filters and is a leading technology company in its field and is a full service solution provider in filtration for separating solids from liquids. As such, this paper compares the new developments in this market area with the prevailing known vacuum filtration technology, but focuses on a comparison between capillary action filters and rotary vacuum disc filters (RVDF). The product name name Larox CC is used to differentiate the Outotec Larox filters from the generic term.