Certain bulk commodities, such as iron ore and coal, utilise the difference in density between the value and the waste material as part of a value-add process before being sent to market. Understanding the density distribution in these materials is therefore critical to both process design for new projects and process control in optimising existing operations.
Traditional density distribution analysis techniques have limitations in determining materials of high densities (above 4g/cc).
Anglo American’s iron ore business, Kumba Iron Ore supported a research project to develop an alternative density separation technique to achieve this for the characterisation of low grade iron ores.
Shamudulu Shamaila, senior metallurgist at Anglo American’s mining and technology division, elaborates on the exciting technique that has been developed, embodying two of the group’s core values – safety and innovation.
Shamaila puts it in laymans terms: “Some of these commodities that we process generally are metallurgical. We need to exploit their density differences, in order to separate valuable material from waste material. Maybe your waste material has a lower density than the valuable material. In the case of iron ore, the processes that we use to achieve that, for us to design those processes or to control those processes and module designs we need to have an understanding of the density distribution in the material that we are feeding into the system. That is called a 'washability analysis'. Traditionally what we have used to do that analysis is what is called 'sink-float analysis', which uses fluids and others. Now the X-ray washability monitor has created an alternative method which uses electronics. It has also gone a step further by providing the capability to look at each sample, particle by particle. So we can get data with a higher resolution.”
That is all good and well, but why is this new technology so important?
Shamaila says the need for the new technology was identified by Anglo American's iron ore business, Khumba Iron Ore. He said the company was in the forefront of innovation in the industry and one of its main focusses in this area was to share knowledge and research findings for the benefit of the entire mining and minerals sector.
“For us as a group this provides a platform for other divisions to know that this capability is being developed and they can then find ways of leveraging on this development,” he said.
Shamaila said as part of Khumba's production expansion, the company is focusing a lot of attention on research and capacity development.
“Khumba will in future be treating what is called low grade iron ores which have not traditionally been treated. In order to do that, it was necessary to do this feasibility analysis, and this was one of the factors that motivated that development. That's when the partnership was formed between Khumba and German company JC Bachmann. The proof of contact unit was then put together, but first they had to undergo vigorous testing and that is when Anglo American Technical Solution got involved, to provide the research input into it. This development has taken place over three years. In this three years, research has been putting the unit through various technical tests and motivating for and driving the modification of the unit to more specifically to deliver the desired outcome. Now we have reached the point where we have validated it for laboratory application,” he said.
The manager for iron ore and coal at Anglo American’s mining and technology division, Sandip Naik, said Anglo's technical solutions division provides support to all business units within the company.
“The X-ray Transmission Washability Monitor project is just one of them. We have about 250 staff members at research, who are dedicated to provide this kind of support to the business units.
Shamaila said the monitor had three key components, an optical section, radio metric section and a sorting section. The material is presented first to the optical section on a conveyor belt. In the optical section digital images are generated of the particles of the substance. Apart from the digital images, we also extract dimension information about the particle. The particles then move to the next section which is the radiometric section where the particles are radiated with X-rays transmission a similar operation as a baggage scanner at the airport, to get X-ray images. So that gives us some atomic information about the particle. Then through a computer processing unit those images are and the density is calculated and derived. In the sorting section, we have assigned a density ranger who sorts the material according its various densities. At that point we already have statistical information about the density distribution in the sample,” he said.
Shamaila says time is money and because the process has been shortened substantially, this will boost production.
“The project was motivated by the need to do analysis at higher paces than we could before. So this presents an option and the capability to do that analysis that can lead to future production expansion. Secondly this is technology that can potentially be applied online at a plant. This is contribution to the development of the mine of the future. This makes it possible for process engineers get information about what the process is doing in real time as opposed to taking samples from the plant to a laboratory which takes time,” he said.
Naik said the success of the project boosted Anglo's quest to keep up with technology.
“These sort of technologies are a great way forward for us. It means we can produce better metals quicker,” he said.
He said it was important for Anglo to make sure that they contribute to knowledge that is out there in the mining industry and continue being in the forefront of that knowledge.