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Boucher D.,McGill University | Deng Z.,McGill University | Leadbeater T.,University of Birmingham | Langlois R.,McGill University | And 2 more authors.
Minerals Engineering | Year: 2014

Future improvements of gravity concentrators require an increased knowledge of the mechanics behind the separation, including the motion of the particles. This work details the investigation of particle motion through a spiral concentrator. The results of tracking the motion of individual particles using the positron emission particle tracking (PEPT) technique are described. Tracer particles of different sizes and density were tracked along the trough of a laboratory scale spiral. Multiple passes of one tracer through the spiral are combined to represent the bulk of flow of this particle type and size, with the position and time recorded to allow for the particle trajectory and speed to be determined. Finally, the use of PEPT will be shown to be a powerful method to visualise the behaviour of particles during the concentration process, providing data that will be used for the validation of new models of spiral concentrator performance. © 2014 Elsevier Ltd. All rights reserved. Source


Halt J.A.,Michigan Technological University | Nitz M.C.,Michigan Technological University | Kawatra S.K.,Michigan Technological University | Dube M.,COREM
Mineral Processing and Extractive Metallurgy Review | Year: 2015

Iron ore pellets abrade during handling and produce dust. This study was conducted to determine what factors affect pellet dustiness, and whether dustiness can be related to the abrasion index. Factors studied included bed depth within a straight grate furnace; pellet chemistry; firing temperature; coke breeze addition; and tumble index. Abrasion indices for all pellet samples ranged from 1.9-5.0% (20 samples) and from 7.1-27.5% (5 samples). Pellets were dropped in an enclosed tower, which enabled the collection of airborne particles generated during pellet breakdown. The quantity of airborne particles generated by each pellet type was 10-100 mg/kg-drop, or 50-500 mg/kg over five drops through the tower. Pellet dustiness was predominantly affected by pellet chemistry and by pellet firing temperature. Results showed a nearly 21% increase in dustiness for every percent decrease in firing temperature-this was based on a typical firing temperature of 1280°C. Pellet dustiness was regressed to the pellet abrasion index (for AI < 5%), which yielded a correlation coefficient of 0.22. These results show that, although AI is one of the best indicators of fired pellet quality and can indicate high levels of dust, it could not explain the dustiness of good quality pellets.The second paper (Iron Ore Pellet Dustiness Part II) explains the relationship between AI and dust for good-quality pellets; and compares fines generation between pellets fired in Straight-Grate (Traveling Grate) and Grate-Kiln furnaces. © 2015 Taylor and Francis Group, LLC. Source


Sadeghi M.,Laval University | Bazin C.,Laval University | Renaud M.,COREM
International Journal of Mineral Processing | Year: 2016

Spiral concentrators are used in the iron ore industry to separate heavy iron oxide carrier particles from the light silica ones. Losses of iron occur mainly in the fine (- 75 μm) and coarse (+ 600 μm) size fractions. This paper analyzes the radial distribution of iron oxide and silica particles in the reject of a 7 turn spiral. A splitter divides the reject flow into six (6) streams that can be sampled individually. Results show that coarse iron carrier particles settle mainly in the inner part of the spiral trough. Although fine iron particles are mostly concentrated in the outer part of the spiral trough, a significant proportion of these particles remain captive close to the concentrate ports. Coarse silica particles (+ 600 μm) are not concentrated in the innermost part of the spiral trough, while a significant concentration of silica particles in the size range of 75 to 212 μm is found close to the concentrate ports. This observation is coherent with the size of the silica particles that contaminate the spiral concentrate. © 2016 Elsevier B.V. All rights reserved. Source


Bazin C.,Laval University | Sadeghi M.,Laval University | Renaud M.,COREM
Minerals Engineering | Year: 2015

Spirals are gravity concentrators used for the valorization of coal and heavy minerals. Coarse hematite iron ores in Canada are usually concentrated by spirals. Spirals classify the particles according to their size and specific gravity. Several mathematical models were proposed to simulate the operation of spirals using a balance between the various forces acting on particles. However few models provide a method to account for wash water addition and the opening of concentrate ports that are two strategic variables for the operation of spiral classifiers. This paper proposes a model to incorporate these variables in a simulation scheme and validates the model with pilot plant data. © 2015 Elsevier Ltd. Source


Patent
Corem | Date: 2014-11-03

A process for recovering a precious metal from ore includes adding process water containing thiocyanates to ore particles to obtain a pulp. The pulp having a basic pH is contacted with an oxidizing gas containing ozone; and the pulp is contacted with cyanide. Contacting the pulp with cyanide can include adding cyanide subsequently to contacting the pulp with the oxidizing gas containing ozone.

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