Determination of mineral composition from elemental assays

Zhang, Ning (2000). Determination of mineral composition from elemental assays Master's Thesis, School of Engineering, The University of Queensland.

       
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Author Zhang, Ning
Thesis Title Determination of mineral composition from elemental assays
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2000
Thesis type Master's Thesis
Supervisor Dr W. Whiten
Dr T. Kojovic
Total pages 149
Collection year 2001
Language eng
Subjects L
290702 Mineral Processing
640399 Other
Formatted abstract
This thesis is about determination of mineral composition from elemental assays using least squares techniques. The main research in this thesis is to provide several optimisation methods to reduce the effect of errors in the input data.

Least squares is very effective in solving the problem in which all data are affected by errors. Therefore, a wide range of least squares methods are examined, also a section of original work on the nature of the least squares minimum is presented.

To use least squares methods properly estimates of the accuracy of the sample assays and standard mineral assays had to be obtained. The methods developed to estimate these are described.

Three different methods of calculating mineral composition based on the non-linear least squares (NNLS) algorithm are described and compared in this thesis. The method using weights is the best among these three in terms of accuracy and overheads.

Obviously the errors of input data introduce inaccuracy into the estimates of mineral composition. In this thesis a linear approximation and four bootstrap methods are used to obtain accuracy estimates for the calculated mineral composition. Bootstrap methods repeatedly produce the typical amount variation using one data set by adjusting the data and/or calculation method. They can be applied to many situations once a suitable variation model is determined.

Standard assays are the elemental composition of each of the pure minerals. Their accuracy also affects the accuracy of the calculated mineral composition. A method to obtain standard assays after calculating the mineral composition of multiple samples is also developed.

The mineral composition programs were developed in Matlab. They were designed to accommodate any number of chemical assays, minerals, and different separations. The comparison between the results obtained by using these programs and by using empirical methods shows that the least squares techniques developed employing the research in this thesis are suitable for this kind of situation, and they have been properly implemented in computer code.
Keyword Determination of Mineral Composition
Elemental Assays
Least squares method

Document type: Thesis
Collection: UQ Theses (non-RHD) - UQ staff and students only
 
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Created: Fri, 24 Aug 2007, 17:39:13 EST