Continuous Improvement in the Development of Cold Agglomeration Process to Add Value to Manganese-rich Waste Streams

Abstract

World-Class Organisations strive to move away from linear economy to circular economy, where fundamental objectives are to eliminate waste and continual utilisation of resources. Circular economy and sustainability is also critical to the mining industry. Manganese mining operations and the smelting industry inherently generate Manganese rich by-products that are not saleable due to their small particle size. The bulk source of fine-sized by-products being evaluated are bag-house dust collected during smelting (below 100 microns), and ultra-fines (slimes) generated during beneficiation of the ore (below 300 microns). Other sources of fines are, among others: bag-house dust collected from conveyor systems and metal crushing and screening (below 100 microns), fines generated upon metal crushing (-3mm)) and fines from Metal Recovery Plant (-3mm). These waste streams are traditionally accumulated in lined tailings storage facilities that require continuous management to reduce environmental risk. In 1998, Assmang Manganese took an informed decision to investigate different ways on how to re-use such by-products. This paper firstly summarizes Assmang Cato Ridge experience in developing and identifying the most efficient, effective and flexible cold agglomeration process that can add value to Manganese rich waste streams. Such development aims to increase the utilization of waste streams, through agglomeration of current arising and historical furnace dust and other by-products generated during smelting operation, as well as the manganese ultra-fine ore generated at Assmang Manganese Mines. The paper examines four different cold agglomeration processes (Block or Brick-Making, Roll Press, Extrusion and High Compression-Vibration) that have been trialled by Assmang over the years. A High Compression Vibration cold-agglomeration technology, currently in use by Cato Ridge, has demonstrated unique capabilities to achieve competent agglomerates that meet critical metallurgical requirements. The use of agglomerates has become a significant part of the burden charge in the production of HCFeMn in Submerged Arc Furnaces (SAF) at Cato Ridge. The physical characteristic of agglomerates that Cato Ridge targets to feed its SAF charging bins are: maximum 10% fines below 6.0mm, minimum Shatter Index of 93% and minimum Compressive Strength of 5.0 MPa. The critical chemical composition required is Manganese content of 37% and Manganese to Iron ratio of 5.5.