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Arvidson B.R.,Bo Arvidson Consulting LLC | Norrgran D.,Eriez Magnetics
Mineral Processing and Extractive Metallurgy: 100 Years of Innovation | Year: 2014

Larg e-scale magnetic separation processes became viable with the advance of commercial permanent magnets in the 1940s. Magnetite ores could then be efficiently processed at low cost. Weakly magnetic, relatively high-value minerals could be processed by the turn of the 19th century with low-capacity electromagnetic separators and from the 1930s with induced roll electromagnetic separators. Thirty years later, high-intensity magnetic separators for high-capacity processing of non-magnetite iron ores became available, complementing other beneficiation methods. Shortly thereafter, high-gradient versions of high-intensity magnetic separators were developed, impacting the kaolin clay processing industry and later some other minerals applications. More recently, a further version of the high-gradient magnetic separator (HGMS) type has benefitted the non-magnetite iron ore industry. In 1981, the first high-intensity magnetic separator based on powerful rare-earth magnets was developed and with further advances changed the industrial minerals industry. Superconducting magnets for ore processing were introduced in commercial scale in the early 1980s and later generations changed the kaolin clay processing industry again. The paper will give an overview of the historical developments of magnetic separation for minerals, the impact on the ore processing industry as well as major application examples. An overview of designs is included, but detailed explanations of the operational features and comparisons will be given only as examples because some technologies tend to replace prior art and the interested reader may easily find plenty of literature on such subjects. Other important magnetic separation uses, such as removal of tramp iron, metals recycling and filtration of waste water are not included.

Arvidson B.R.,Bo Arvidson Consulting LLC | Wotruba H.,RWTH Aachen
Mineral Processing and Extractive Metallurgy: 100 Years of Innovation | Year: 2014

While manual ore sorting has been reported since the beginning of mining history, significant advances have been made recently in various sensing technologies in recent years. As the equipment/systems relative costs are reduced, machine sorters are showing an increased impact on the mining industry, specifically in areas such as uranium and magnesite processing. This paper reviews the initial adaptation of food sorters to optical ore sorters, specific radiometric sensing sorters for uranium ores to the modern photometric, and several sensing technologies based sorters.

Arvidson B.R.,Bo Arvidson Consulting LLC
Transactions of the Indian Institute of Metals | Year: 2013

On an average global basis, iron ores tend to decrease in Fe grade over time. With the exception for some deposits that are logistically challenged, iron ore resources in more accessible areas may often have processing issues, especially if high-grade concentrates are desired. This paper addresses some of these with examples on how technological developments enhanced the feasibility to exploit such ores. The emphasis is on comminution, magnetic separation and flotation. © 2013 Indian Institute of Metals.

Arvidson B.,Bo Arvidson Consulting LLC | Klemetti M.,Geological Survey of Finland | Knuutinen T.,Geological Survey of Finland | Kuusisto M.,Geological Survey of Finland | And 2 more authors.
Minerals Engineering | Year: 2013

Northland Resources is developing several magnetite mineral resources in northern Europe. The Tapuli, Sahavaara and Pellivuoma mineral resources are in Sweden and the Hannukainen resource is in Finland. Three of these resources (Sahavaara, Pellivuoma and Hannukainen) require flotation to remove more than 98% by mass of the sulphur in the feedstock to produce a saleable magnetite concentrate with a sulphur level below 0.05% w/w. The detrimental sulphur containing mineral is monoclinic pyrrhotite and its removal requires flotation. Previous published results related to pyrrhotite flotation from magnetite concentrate, e.g. on a magnetite deposit in Peru, only required the process to produce a final magnetite concentrate with a sulphur level below 0.4% w/w. There is currently no known published information on a process that floats pyrrhotite to achieve a magnetite concentrate with less than 0.05% w/w of sulphur. Extensive bench-scale tests were conducted on samples from Sahavaara, Pellivuoma and Hannukainen. Low-intensity magnetic separation (LIMS) tests showed that LIMS upgraded the magnetite and the sulphur in the pyrrhotite at the same ratio. The final flotation reagent regimes and conditions for each deposit were different being related to differences in mineralogy and grind size. The pH ranged from natural to pH of 4. Large dosage rates of xanthate collectors and long flotation times were needed. Flotation feed percent solids of between 45% and 50% w/w was required. Future work will modify these reagent regimes and flotation conditions in the full-scale plants to further optimise the flotation processes. © 2013 Elsevier Ltd. All rights reserved.

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