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Amelunxen P.,Aminpro Peru S.A.C. | Sandoval G.,Aminpro Chile SpA | Barriga D.,Aminpro Chile SpA | Amelunxen R.,Aminpro Chile SpA
Minerals Engineering | Year: 2014

This paper presents a critical review of the role of froth recovery in laboratory flotation kinetics tests. By conducting tests in the standard lab equipment (the Denver cell), it is demonstrated that, for typical scraping rates, the froth recovery is significantly lower than the 100% that is commonly assumed when interpreting lab kinetics data. Furthermore, it is shown that the curve of overall rate constant versus froth residence time, as defined by the scraping rate, is not linear, but increases quickly at faster scraping rates. These findings have important implications for scale-up. For one, differences in froth recoveries at the lab scale can lead to significant error in the modeled plant recoveries. For two, they undermine a key assumption used to derive and validate the linear relationship between collection rate constant and bubble surface area flux. This casts doubt on the assertion that it is only the collection rate - rather than the froth recovery, interface recovery, or some combination thereof - that is responsible for the observed collinearity between the bubble surface area flux and the overall rate constant. © 2014 Elsevier Ltd. All rights reserved.

Amelunxen P.,AME Ltda | Berrios P.,Aminpro Chile SpA | Rodriguez E.,Aminpro Chile SpA
Minerals Engineering | Year: 2014

In this paper, the authors undertake a critical review of the Starkey test and the publicly available information related to the test equipment, procedures, and scale-up methodology. The following recommendations are proposed to improve the test method: The test should be conducted for a fixed grinding time of 120 min, regardless of the time required to reach 80% passing Tyler #10 mesh.The test should be conducted with constant time intervals of 15, 30, 60, and 120 min (cumulative) in order to facilitate the application of geostatistics to the resulting index values. This would also allow for multiple tests to be conducted in parallel (through the use of multiple mill rollers).The feed size should be prepared using a more rigorous procedure to ensure constant mass in each of the course screen fractions.The curve of finished product versus time should be modeled and the resulting index calculated from the model for a standard feed size distribution, so that errors attributable to the sample preparation step are minimized. The improved feed preparation steps and the use of constant grinding intervals enables the development of a faster alternative to the standard test that is more cost effective for high volume geometallurgical programs. In addition to the updated procedures, a new calibration equation is proposed, with calibration factors for pebble crushing, fine feed and autogenous grinding, based on information in the public literature. Detailed descriptions of the test equipment, procedures, and calibration are provided, and it is proposed that this become an open standard procedure for SAG mill hardness testing, particularly for soft to medium-hard ores, over which range the test is most effective. © 2013 Elsevier Ltd. All rights reserved.

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