Engineering & Mining Journal

AUG 2014

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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AUGUST 2014 • E&MJ; 47 www.e-mj.com F LO TAT I O N of reagents for the reverse flotation of phosphate and iron ore. Lee (Orica) looked at a different aspect of technology developments. A major improvement in flotation optimization has been the increasing use of automated quantitative ore characterization to assist in tailoring flotation reagent schemes for specific mine operations. Automated min- eralogy analytical techniques typically involve Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spec- troscopy (EDS), he said. For Nalco, Paulson told E&MJ; that important developments have included the development of reagents that provide greater selectivity as well as improved com- bination collectors for copper and molyb- denum circuits. Another advance, he added, has been the development of col- lectors with improved health and safety characteristics, such as the company's CoalEx collectors for coal flotation. Westpro's Taplin commented that new frother developments have been the key chemistry change in the past 10 years, from its experience. The movement away from the typical alcohol-based MIBC to more aggressive high-molecular structure glycol-based frothers has allowed milling operations to grind coarser but still have high metal recovery. Bubble strength has been enhanced because of the nature of the glycol-based frothers. Wasmund (Eriez) pointed out that con- tinued improvement in selectivity is a major advance. "As we continue to con- sume the 'easier' orebodies, it is becoming necessary to continually develop reagents that are more selective with regards to complex mineralogy," he said. Increased Ore Complexity Also, E&MJ; asked respondents how the reagent industry is addressing the problem that orebodies are becoming more complex in terms of their mineralogy. Gould: As ores become more complex, separation requires more selective collectors to operate in more complex flowsheets. Reagents are being developed that are more selective in the roughers, and especially more selective in the cleaners and scavengers. This has become a major area of research. Taplin: One of the key areas is the development of new collectors due to the limited number of high-sulphide copper orebodies, and the increasing amount of oxide ore blended with sulphides. New col- lector development is targeted to allow for better recoveries using DTP, mercaptons and hydroxamate chemistries, increasing the typical low recoveries associated with oxide-blended ores. Paulson: The increased complexity of orebodies and higher variability in mineralo- gy drives the need for more customized pro- grams. Nalco is addressing this by perform- ing detailed mineralogy studies and then developing tailored reagents with improved performance for a given set of conditions. This gives the operator flexibility in changing reagents as the mine plan progresses. Wasmund: The industry is addressing complex mineralogy by conducting more bench-top and laboratory-scale flotation evaluations, both on new projects and existing concentrators. It is an adage in our business that the best metallurgical results are obtained by a simultaneous optimization of ore charac- teristics, reagent chemistry and flotation equipment, and this is especially true for complex mineralogy. Lee: Oxide flotation and reverse flota- tion techniques are increasingly being used to maximize mineral recovery in more com- plex orebodies. This has led to the devel- opment of novel collectors such as hydrox- amates for oxide flotation and amine-based collectors for reverse flotation in the iron- ore industry. Traditionally controlled potential sul- phidization (CPS) has also been used suc- cessfully to recover oxide and surface oxi- dized minerals using conventional sulphide collectors, which is a more complex process- ing route when compared to the novel oxide collectors but normally is more cost-effective. Velgaard: The reagent strategy is de- pendent on the source of the complexity, which can include the particle liberation size, the types and qualities of any inter- fering minerals or water-chemistry impacts. In addition, the range of ore response within the same orebody can vary widely, posing flotation chemical suite optimiza- tion challenges. There is usually no single "magic bul- let" flotation reagent chemistry suite com- bination that will be the optimum, so it is incumbent on suppliers to test and devel- op flotation reagent suites that offer the best response to individual ores. Tailor-made Reagents E&MJ; then asked the respondents for their advice on how reagent suppliers can best tailor their products to meet the needs of individual mines. Paulson: Knowing the mineralogy as well as the process and operational condi- tions to then combine chemistries that suit the specific ore type. And also, to provide timely technical assistance when changes or adjustment in the programs are needed, he added. Taplin: The key before tailoring any chemical cocktail is to understand fully what needs to be floated. More and more mining operations use the following three factors before making any reagent decision: A Metso 300-m 3 cell. The company is currently designing cells with capacities of up to 660 m 3 .

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