The application of sampling theory in bauxite protocols

Bortoleto, Daniel Armelim; Chieregati, Ana Carolina; Pereira, Antônio Henrique Rietra; Oliveira, Raiza Cavalcante

doi:10.1590/s0370-44672014000200014

Cited by 4 publications

(2 citation statements)

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“…Research describes the experimental procedures for the calibration sampling parameters i.e. segregation-free analysis, heterogeneity test, and sampling tree experiments [17]. The calibration is necessary to reduce the sampling error caused by minimum representative sample masses.…”

Section: Composite Sampling Applicationsmentioning

confidence: 99%

Upgraded Analytical Protocols in Bauxite Refining Industry Using Composite Sampling Approach to Minimize Laboratory Analysis Load

AlDossari¹

2023

MSA

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The laboratories in the bauxite processing industry are always under a heavy workload of sample collection, analysis, and compilation of the results. After size reduction from grinding mills, the samples of bauxite are collected after intervals of 3 to 4 hours. Large bauxite processing industries producing 1 million tons of pure aluminium can have three grinding mills. Thus, the total number of samples to be tested in one day reaches a figure of 18 to 24. The sample of bauxite ore coming from the grinding mill is tested for its particle size and composition. For testing the composition, the bauxite ore sample is first prepared by fusing it with X-ray flux. Then the sample is sent for X-ray fluorescence analysis. Afterwards, the crucibles are washed in ultrasonic baths to be used for the next testing. The whole procedure takes about 2 -3 hours. With a large number of samples reaching the laboratory, the chances of error in composition analysis increase. In this study, we have used a composite sampling methodology to reduce the number of samples reaching the laboratory without compromising their validity. The results of the average composition of fifteen samples were measured against composite samples. The mean of difference was calculated. The standard deviation and paired t-test values were evaluated against predetermined critical values obtained using a two-tailed test. It was found from the results that paired test-t values were much lower than the critical values thus validating the composition attained through composite sampling. The composite sampling approach not only reduced the number of samples but also the chemicals used in the laboratory. The objective of improved analytical protocol to reduce the number of samples reaching the laboratory was successfully achieved without compromising the quality of analytical results.How to cite this paper: AlDossari, F.M.

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Section: Composite Sampling Applicationsmentioning

confidence: 99%

Upgraded Analytical Protocols in Bauxite Refining Industry Using Composite Sampling Approach to Minimize Laboratory Analysis Load

AlDossari¹

2023

MSA

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“…To tackle this drawback, the use of protocols that lead to the calibration of the system under study is recommended. An example, applied to samples of bauxite, is developed by Bortoleto et al (2014).…”

Section: Process Variabilitymentioning

confidence: 99%

Error variance of short duration sieving

Resende¹,

Luz

2018

REM, Int. Eng. J.

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In this study, the variance of ordinary sieving test error was determined concerning the specification limit of sized iron ore product by subtracting the fundamental error (described by the Gy's formalism for sampling), from the global error (recoverable from database of historical values). The results allowed the calculation of the confidence interval for the percentage of material finer than the upper screen specification limit. Thereafter, a method to estimate the so-called effectiveness coefficient of the screening operation was developed, which is the ratio between number of particle presentations to passage and the number of oscillations during the material shaking on the screen surface. This estimation was based on the probability statements and particle size distribution of the feed. Considering the size distribution of the products tested in this study, the results have shown that the sieving time could be reduced when determining the percentage of material finer than the upper specification mesh.

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Heterogeneity test for optimising nickel sampling protocols

Fernandes

Vargas²,

Chieregati

2020

REM, Int. Eng. J.

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Fundamental Sampling Error (FSE) is generated whenever a sample is taken from a lot of particulate material and is caused by an intrinsic characteristic of every mineral deposit: the constitutional or intrinsic heterogeneity of the ore. FSE is the only error that can never be eliminated in sampling processes, but it can be reduced to acceptable values. The optimisation of sampling protocols is based on the minimisation of FSE and is essential to reduce the deviations of grade estimates for mine planning, process control and mine-to-mill reconciliation. In order to calculate minimum sample masses and to optimise sampling protocols, heterogeneity studies have been developed. The original heterogeneity test (HT), proposed by Gy (1967) and Pitard (1993; 2009), is an experimental method of obtaining the intrinsic heterogeneity (IH L). Most of the heterogeneity studies available in Brazilian literature have been performed on gold deposits, which have higher intrinsic heterogeneity due to the nugget and cluster effects and low grades, unlike base metal deposits. Nickel ores have never been the focus of heterogeneity studies in Brazil or worldwide. Therefore, the factors that compose IH L have never been validated for nickel ores, which was the objective of this article. Based on the results of the heterogeneity test performed on a nickel ore from Niquelandia, Brazil, the standard deviations of FSE were calculated at each stage of the sampling protocol. An optimised protocol is proposed herein, in which the total deviation of FSE is below the maximum value recommended by Pierre Gy's Theory of Sampling (TOS).

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The application of sampling theory in bauxite protocols

Cited by 4 publications

References 1 publication

Upgraded Analytical Protocols in Bauxite Refining Industry Using Composite Sampling Approach to Minimize Laboratory Analysis Load

Upgraded Analytical Protocols in Bauxite Refining Industry Using Composite Sampling Approach to Minimize Laboratory Analysis Load

Error variance of short duration sieving

Heterogeneity test for optimising nickel sampling protocols

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