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Mwanga, Abdul
Publications (10 of 12) Show all publications
Mwanga, A., Parian, M., Lamberg, P. & Rosenkranz, J. (2017). Comminution modeling using mineralogical properties of iron ores. Minerals Engineering, 111, 182-197
Open this publication in new window or tab >>Comminution modeling using mineralogical properties of iron ores
2017 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 111, p. 182-197Article in journal (Refereed) Published
Abstract [en]

Comminution modeling aims to predict the size and liberation distribution of mineral particles and the required comminution energy. The current state-of-the-art comminution models provide a calculation of neither particle size distribution, grinding energy and throughput dependency with neither a broad understanding of how the mineral grade varies by size nor the liberation distribution of the product. The underlying breakage mechanisms affect the liberation of mineral grains and are dependent on modal mineralogy and mineral texture (micro structure). It has also been a challenge to model comminution systems to predict the optimal energy and size for better mineral liberation because of the variability of the mineral particle properties i.e. grains arrangement and composition. A detailed mineralogical study was carried out in order to broaden the understanding of the nature and distribution of comminuted particles in a ball mill product. Focusing on iron ore samples the study showed how the particle breakage rate decreases when the particles reach the grain size of the main mineral component. Below that size, comminution does not increase mineral liberation and therefore in most of the cases passing over that boundary is only a waste of energy. The study involving iron ores from Malmberget and Kiruna, Northern Sweden, showed that certain shortcuts can be applied to empirically model the mineral liberation distribution of the particles in a ball mill based on the mineral grade-by-size pattern from a geometallurgical program. In Malmberget and Kiruna the mineral grade-by-size pattern is depending on the mineral distribution and grain size of gangue as well as magnetite or hematite minerals. A significant difference between mineral breakage of the same grade and gangue minerals can be observed due to texture differences.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-64658 (URN)10.1016/j.mineng.2017.06.017 (DOI)000406729800020 ()2-s2.0-85021449830 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-06-29 (andbra)

Available from: 2017-06-29 Created: 2017-06-29 Last updated: 2018-07-10Bibliographically approved
Mwanga, A., Rosenkranz, J. & Lamberg, P. (2017). Development and experimental validation of the Geometallurgical Comminution Test (GCT). Minerals Engineering, 108, 109-114
Open this publication in new window or tab >>Development and experimental validation of the Geometallurgical Comminution Test (GCT)
2017 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 108, p. 109-114Article in journal (Refereed) Published
Abstract [en]

Based on the requirements and available sample amounts in geometallurgical studies of ore variability, a small scale batch grindability test has been developed, the Geometallurgical Comminution Test (GCT). The test requires 220 g of sample material and can be conducted within 2.5–3 h. Test results are evaluated using a modified Bond equation together with a linear correlation factor. The test and evaluation method have been validated against several ore types.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-62968 (URN)10.1016/j.mineng.2017.04.001 (DOI)000401381700011 ()2-s2.0-85017273141 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-05-02 (rokbeg)

Available from: 2017-04-10 Created: 2017-04-10 Last updated: 2018-09-13Bibliographically approved
Mwanga, A., Rosenkranz, J. & Lamberg, P. (2015). A Comminution Model for Linking Size Reduction with Energy and Mineral Liberation (ed.). Paper presented at European Symposium on Comminution and Classification : 07/09/2015 - 11/09/2015. Paper presented at European Symposium on Comminution and Classification : 07/09/2015 - 11/09/2015.
Open this publication in new window or tab >>A Comminution Model for Linking Size Reduction with Energy and Mineral Liberation
2015 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Traditionally comminution models are used to predict size reduction and the energy required for that. For better control of energy and quality of concentrate grade in subsequent concentration processes also the liberation of the minerals has to be considered. Mechanical forces are used to break the bonds of the mineral matrix of composite particle into mineral phases.Mineral composition and texture (i.e. the grain size) have been used to predict the breakage properties of an ore but are not fully used to predict the liberation of mineral particles during comminution. For this purpose an integrated breakage model is needed that links the energy used to reduce the size of the mineral particles with the mineral liberation achieved during comminution. Such a liberation model for forecasting the degree of mineral liberation has to be based on mineral texture information.As a novel approach, a liberability curve for various mineral textures has been developed and used to optimize the particle size and energy required for ore comminution. Tests with iron ore samples from the Malmberget mine in Northern Sweden show that, liberation and breakage of the mineral particles are controlled by the grade distribution and grain size of magnetite.

National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-31560 (URN)5c778380-cd85-4baa-b795-2adf662c6dd7 (Local ID)5c778380-cd85-4baa-b795-2adf662c6dd7 (Archive number)5c778380-cd85-4baa-b795-2adf662c6dd7 (OAI)
Conference
European Symposium on Comminution and Classification : 07/09/2015 - 11/09/2015
Note
Godkänd; 2015; 20150914 (abdmwa)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Mwanga, A., Lamberg, P. & Rosenkranz, J. (2015). Comminution test method using small drill core samples (ed.). Paper presented at . Minerals Engineering, 72, 129-139
Open this publication in new window or tab >>Comminution test method using small drill core samples
2015 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 72, p. 129-139Article in journal (Refereed) Published
Abstract [en]

Comminution tests aim to measure the comminution properties of ore samples to be used in designing and sizing the grinding circuit and to study the variation within an ore body. In the geometallurgy context this information is essential for creating a proper resource model for production planning and management and process control of the resource’s exploitation before and during production.Standard grindability tests require at least 10 kg of ore sample, which is quite a lot at early project stages. This paper deals with the development of a method for mapping the variability of comminution properties with very small sample amounts. The method uses a lab-scale jaw crusher, standard laboratory sieves and a small laboratory tumbling mill equipped with a gross energy measurement device. The method was evaluated against rock mechanics tests and standard Bond grindability test. Within this approach textural information from drill cores is used as a sample classification criterion.Experimental results show that a sample of approximate 220 g already provides relevant information about the grindability behavior of iron ores at 19% mill fillings and 91% fraction of the critical mill speed. The gross energy measured is then used to calculate an equivalent grinding energy. This equivalent energy is further used for predicting the variations in throughput for a given deposit and process.Liberation properties of the ore connected to grindability elaborates energy required for grinding and significances of it when deciding to move to higher grinding energy considering the improvement of liberation of the desired mineral. However, high energy significantly enhanced the degree of liberation of magnetite and is expected to improve the concentrate grade after downstream treatment. The higher the magnetite content the better is the liberability of magnetite and the lower the energy required to liberate the desired mineral. Liberability of magnetite is also affected by texture classes containing low magnetite content. A methodology that combines this information has been developed as a practical framework of geometallurgical modeling and simulation in order to manage technical and economic exploitation of resource at early, project stages and during mining operations.

National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-3145 (URN)10.1016/j.mineng.2014.12.009 (DOI)000350078700018 ()2-s2.0-84925689347 (Scopus ID)0eeb82bd-ad49-4475-b715-2f8b24f6f02d (Local ID)0eeb82bd-ad49-4475-b715-2f8b24f6f02d (Archive number)0eeb82bd-ad49-4475-b715-2f8b24f6f02d (OAI)
Note
Validerad; 2015; Nivå 2; 20150126 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mwanga, A., Rosenkranz, J. & Lamberg, P. (2015). Testing of Ore Comminution Behavior in the Geometallurgical Context: A Review (ed.). Paper presented at . Minerals, 5(2), 276-297
Open this publication in new window or tab >>Testing of Ore Comminution Behavior in the Geometallurgical Context: A Review
2015 (English)In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 5, no 2, p. 276-297Article in journal (Refereed) Published
Abstract [en]

Comminution tests are an important element in the proper design of orebeneficiation plants. In the past, test work has been conducted for particular representative reference samples. Within geometallurgy the entire ore body is explored in order to further identify the variation within the resource and to establish spatial geometallurgical domains that show the differential response to mineral processing. Setting up a geometallurgical program for an ore deposit requires extensive test work. Methods for testing the comminution behavior must therefore be more efficient in terms of time and cost but also with respect to sample requirements. The integration of the test method into the geometallurgical modeling framework is also important. This paper provides an overview of standard comminution test methods used for the investigation of ore comminution behavior and evaluates their applicability and potential in the geometallurgical context.

National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-11089 (URN)10.3390/min5020276 (DOI)000357152700010 ()2-s2.0-84937570822 (Scopus ID)9feff2e8-03ce-468e-a1bc-f4ef60764a27 (Local ID)9feff2e8-03ce-468e-a1bc-f4ef60764a27 (Archive number)9feff2e8-03ce-468e-a1bc-f4ef60764a27 (OAI)
Note
Validerad; 2015; Nivå 2; 20150519 (abdmwa)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mwanga, A., Rosenkranz, J. & Lamberg, P. (2014). Developing Ore Comminution Test Methods in the Geometallurgical Context (ed.). Paper presented at Conference in Minerals Engineering 2014 : 04/02/2014 - 05/02/2014. Paper presented at Conference in Minerals Engineering 2014 : 04/02/2014 - 05/02/2014.
Open this publication in new window or tab >>Developing Ore Comminution Test Methods in the Geometallurgical Context
2014 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

Comminution tests are necessary in order to investigate mineral liberation achieved during particle size reduction and the mechanical energy needed for that. Depending on the type of the comminution process and equipment respectively, various test methods have been established in the past. Most of these tests require comparatively large sample amounts and are also costly in terms of time.Within the geometallurgical approach comprehensive information about the ore’s processing properties is required for building a spatial geometallurgical model of a deposit. Comminution behavior has to be quantified when modeling mill capacity and liberation. Providing comminution test methods that are efficient in terms of sample utilization and effort is therefore an essential task.This paper summarizes several different approaches to quantifying ore comminution behavior in the geometallurgical context. The methods examined at Luleå University of Technology comprise linking crushing and grinding characteristics to mineralogical parameters as well as correlating them with geotechnical tests, the down-scaling of standard grindability tests, and the further development of drop weight test methods.

National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-27481 (URN)0f40f68a-83fa-4774-b4cc-38b8a5dfb8b6 (Local ID)0f40f68a-83fa-4774-b4cc-38b8a5dfb8b6 (Archive number)0f40f68a-83fa-4774-b4cc-38b8a5dfb8b6 (OAI)
Conference
Conference in Minerals Engineering 2014 : 04/02/2014 - 05/02/2014
Note
Godkänd; 2014; 20140402 (abdmwa)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Mwanga, A., Lamberg, P. & Rosenkranz, J. (2014). Liberability: A new approach for measuring ore comminution behavior (ed.). Paper presented at Process Mineralogy : 17/11/2014 - 19/11/2014. Paper presented at Process Mineralogy : 17/11/2014 - 19/11/2014.
Open this publication in new window or tab >>Liberability: A new approach for measuring ore comminution behavior
2014 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

Crushability and grindability are traditionally used to describe the material properties in comminution. These parameters neglect the main objective of ore comminution, the mineral liberation and therefore information is incomplete. A new concept called liberability: the easiness of mineral liberation in comminution is introduced to fill the gap. Establishing a liberability map of a deposit requires grindability tests and liberation measurements for the grinding product. The liberability curve shows the degree of liberation of the mineral against grinding energy and offers better baseline for resource optimization than the grindability curve. A case study with a magnetite iron ore from Malmberget, northern Sweden, shows that certain shortcuts can be applied to keep the experimental effort reasonable which is important, particularly when applying the liberability in a geometallurgical program. In Malmberget the liberability is depending on the grade and grain size of magnetite. A significant difference between grindability and liberability can be observed.

National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-31239 (URN)55aff270-beb4-4776-89ba-1278bfb7305c (Local ID)55aff270-beb4-4776-89ba-1278bfb7305c (Archive number)55aff270-beb4-4776-89ba-1278bfb7305c (OAI)
Conference
Process Mineralogy : 17/11/2014 - 19/11/2014
Note
Godkänd; 2014; 20141122 (abdmwa)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Mwanga, A. (2014). Test Methods for Characterising Ore Comminution Behavior in Geometallurgy (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå University of Technology
Open this publication in new window or tab >>Test Methods for Characterising Ore Comminution Behavior in Geometallurgy
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Comminution test methods used within mineral processing have mainly been developed for selecting the most appropriate comminution technology for a given ore, designing a grinding circuit as well as sizing the equipment needed. Existing test methods usually require comparatively large sample amounts and are time-consuming to conduct. This makes comprehensive testing of ore comminution behavior – as required in the geometallurgical context – quite expensive. Currently the main interest in the conduct of comminution test lies in the determination of particle size reduction and related energy consumption by grindability test methods, which provide the necessary information about mill throughput. In this procedure mineral liberation is regarded as a fixed parameter due to missing this information in ore characterization as well as a lack of suitable comminution models. However, ignoring the connection between particle size and mineral liberation prevents the scheduling and controlling of the production process from being optimal.For these reasons new comminution tests need to be developed or alternatively the existing test methods need to be suited to geometallurgical testing where the aim is to map the variation of processing properties of an entire ore body. The objective of this research work is on the one hand to develop small-scale comminution test methods that allow linking comminution behavior and liberation characteristics to mineralogical parameters, and on the other hand establish a modeling framework including mineral liberation information.Within the first stage of the study the comminution of drill cores from Malmberget’s magnetite ore, classified by modal mineralogy and texture information, have been investigated. It was found that there is a direct correlation between the mechanical strength of the rock, as received from unconfined compressive or point load tests, and the crusher reduction ratio as a measure for crushability. However, a negative correlation was found between crushability and grindability for the same samples. The grindability showed inverse correlation with both magnetite grade and the magnetite’s mineral grain size. The preliminary conclusion is that modal mineralogy and micro-texture (grain size) can be used to quantitatively describe the ore comminution behavior although the applied fracture mechanism of the mill cannot be excluded.With crushed ore samples from Malmberget also grindability tests and mineral liberation analyses were conducted using laboratory tumbling mills of different size. Starting from the dimensions of the Bond ball mill a modified test method was developed where small size samples of approximately 220 g were pre-crushed and ground in a down-scaled one-stage grindability test. Down-scaling was done by keeping similar impact effects between the mills. Mill speed and grinding time were used for adjusting the number of fracture events in order to receive similar particle size distributions and specific grinding energy when decreasing mill size by the factor 1.63. A detailed description of the novel geometallurgical comminution test (GCT) is given.With respect to ore crushability and autogenous and semiautogenous grinding (AG/SAG) also drop weight tests were conducted. For a more accurate and precise measurement of the energy transferred to the sample a novel instrumented drop weight was used. Initial tests with fractions of drill cores and pre-crushed ore particles showed that the simple energy calculation based on potential energy needs to be corrected. For the future work these tests will be extended to other ore types in order to investigate the effects of mineralogy and to include mineral liberation in comminution models suitable for geometallurgy.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2014
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-18689 (URN)9d806745-6b7d-4719-9d33-6cebc7cd02af (Local ID)978-91-7439-943-1 (ISBN)978-91-7439-944-8 (ISBN)9d806745-6b7d-4719-9d33-6cebc7cd02af (Archive number)9d806745-6b7d-4719-9d33-6cebc7cd02af (OAI)
Note

Godkänd; 2014; 20140402 (abdmwa); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Abdul Mwanga Ämne: Mineralteknik/Mineral Processing Uppsats: Test Methods for Characterising Ore Comminution Behavior in Geometallurgy Examinator: Professor Jan Rosenkranz, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Professor Hakan Benzer, Hacettepe University, Department of Mining Engineering Beytepe, Ankara, Turkey Tid: Torsdag den 12 juni 2014 kl 10.00 Plats: F531, Luleå tekniska universitet

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-01-30Bibliographically approved
Lamberg, P., Rosenkranz, J., Wanhainen, C., Lund, C., Minz, F., Mwanga, A. & Parian, M. (2013). Building a Geometallurgical Model in Iron Ores using a Mineralogical Approach with Liberation Data (ed.). In: (Ed.), Simon Dominy (Ed.), Geomet13: The Second AusIMM International Geometallurgy Conference 2013. Paper presented at AusIMM International Geometallurgy Conference : 30/09/2013 - 02/10/2013 (pp. 317-324). Parkville, Victoria: The Australasian Institute of Mining and Metallurgy
Open this publication in new window or tab >>Building a Geometallurgical Model in Iron Ores using a Mineralogical Approach with Liberation Data
Show others...
2013 (English)In: Geomet13: The Second AusIMM International Geometallurgy Conference 2013 / [ed] Simon Dominy, Parkville, Victoria: The Australasian Institute of Mining and Metallurgy, 2013, p. 317-324Conference paper, Published paper (Refereed)
Abstract [en]

A geometallurgical model is currently built in two different ways. The first and the most common way relies on geometallurgical testing, where a large number of samples are analysed for metallurgical response using small-scale laboratory tests, eg Davis tube testing. The second, mineralogical approach focuses on collecting mineralogical information over the orebody and building the metallurgical model based on mineralogy. At Luleå University of Technology,Sweden, the latter method has been adopted and taken further in four ongoing PhD studies. The geological model gives modal composition by the help of element-to-mineral conversion and Rietveld X-ray diffraction. Texturally, the orebody is divided into different archetypes, and liberation measurements for each of them are carried out in processing fineness using IncaMineral, a SEM-based technique. The grindability and liberation spectrum of any given geological unit (sample, ore block, domain) are extrapolated from the archetypes. The process model is taken into a liberation level by mass balancing selected metallurgical tests using the particle tracking technique. The approach is general and can be applied to any type of ores. Examples of ongoing studies on iron and massive sulfide ores are given.

Place, publisher, year, edition, pages
Parkville, Victoria: The Australasian Institute of Mining and Metallurgy, 2013
National Category
Metallurgy and Metallic Materials Geology
Research subject
Mineral Processing; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-34546 (URN)8c43c586-f40e-4801-a310-0085b0e672fa (Local ID)9781921522901 (ISBN)8c43c586-f40e-4801-a310-0085b0e672fa (Archive number)8c43c586-f40e-4801-a310-0085b0e672fa (OAI)
Conference
AusIMM International Geometallurgy Conference : 30/09/2013 - 02/10/2013
Note

Godkänd; 2013; 20131007 (perlam)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Lamberg, P., Parian, M., Mwanga, A. & Rosenkranz, J. (2013). Mineralogical Mass Balancing of Industrial Circuits by Combining XRF and XRD Analyses (ed.). In: (Ed.), Jan Rosenkranz; Tommy Karlkvist (Ed.), Proceedings Conference in Minerals Engineering 2013: . Paper presented at Conference in Minerals Engineering 2013 : 05/02/2013 - 06/02/2013 (pp. 105-116). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Mineralogical Mass Balancing of Industrial Circuits by Combining XRF and XRD Analyses
2013 (English)In: Proceedings Conference in Minerals Engineering 2013 / [ed] Jan Rosenkranz; Tommy Karlkvist, Luleå: Luleå tekniska universitet, 2013, p. 105-116Conference paper, Published paper (Other academic)
Abstract [en]

Mineralogical information forms a vital basis for designing, diagnosing and optimizing mineral processing circuits. Often modal mineralogical mass balance (i.e. mass balance on mineral grades) is adequate; i.e. liberation data is not required. In analysing mineral grades in process samples automated mineralogy (SEM based image analysis) is mostly used. As this method is tedious, slow, and costly, and has some limitation, an alternative technique was developed by combining quantitative X-ray diffraction (XRD) and chemical assays by X-ray fluorescence (XRF). A case study on magnetic separation test is presented. Method has potential for an automatized off-line technique for providing mineralogical mass balance in majority of mineral processing plants.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2013
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-32232 (URN)6a8de36f-5698-40ca-bcc3-1b3be2523637 (Local ID)978-91-7439-647-8 (ISBN)6a8de36f-5698-40ca-bcc3-1b3be2523637 (Archive number)6a8de36f-5698-40ca-bcc3-1b3be2523637 (OAI)
Conference
Conference in Minerals Engineering 2013 : 05/02/2013 - 06/02/2013
Note
Godkänd; 2013; Bibliografisk uppgift: Conference Proceedings, published as CD-ROM, ISBN 978-91-7439-647-8; 20130702 (janros)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
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