OPTIMIZATION OF FINE GOLD RECOVERY USING A CUSTOMIZED AFFORDABLE VORTEX MACHINE FOR ARTISANAL AND SMALL-SCALE GOLD MINERS
By:
NAME
Supervised by:
1. NAME
Project Code: MMPE - PRO-20-09
DECLARATION
We declare that
...
OPTIMIZATION OF FINE GOLD RECOVERY USING A CUSTOMIZED AFFORDABLE VORTEX MACHINE FOR ARTISANAL AND SMALL-SCALE GOLD MINERS
By:
NAME
Supervised by:
1. NAME
Project Code: MMPE - PRO-20-09
DECLARATION
We declare that this is our original work of the project submitted and to the best of our knowledge; this work has not been submitted anywhere in any university for the award of any other degree.
Student name……………………………Signature……………………….Date…………….
Student name……………………………Signature……………………….Date…………….
Supervisor’s name………………….........Signature………………………….Date……………..
Supervisor’s name………………….........Signature………………………….Date……………..
DEDICATION
We dedicate this work Mr. Peter Mbugua, whose advice and input was invaluable to the project, to God, He who strengthened us through this processes, and finally to our parents, family and friends whose support during the entire period was highly appreciated.
ACKNOWLEDGMENT
We would like to give thanks to Jomo Kenyatta University of Agriculture and Technology university institution for facilitating our degree programme and especially the Mining Materials and Petroleum Department (MMPE) for the support is had accorded us through this process. We would also like to thank our supervisors NAME and NAME for the analytical assessment of our work and their academic input. Finally, we would like to thank Migori County Artisanal Miners Cooperative (MICA) for the chance to work with small-scale and artisanal miners during industrial attachment; where the idea for this project was conceived. We thank you all.
TABLE OF CONTENTS
DECLARATION 2
DEDICATION 3
ACKNOWLEDGMENT 4
ABSTRACT 9
CHAPTER ONE 10
INTRODUCTION 10
Background 10
Study Area 11
Geology and Mineralization 11
Problem statement 12
Research objectives 13
Overall objective 13
Specific objectives 13
CHAPTER TWO 14
LITERATURE REVIEW 14
2.1 Gold and Its properties 14
2.1.1 Fine gold 14
2.1.2 Gold properties 15
2.2 Gold comminution 16
2.3 Gold concentration methods in ASM communities 17
2.3.1 Traditional Sluices 17
2.3.2 Panning 17
2.4 Vortex machine 19
2.4.1 Working principle 19
CHAPTER THREE 24
RESEARCH METHODOLOGY 24
3.1 Expected outcome 24
3.2 Questionnaire 24
3.2.1 Findings 25
3.2.2 Analysis of the questionnaire 26
3.2.3 Recommendations 28
3.2.4 Design 29
3.2.5 Data collection and participants 29
3.2.6 Requirements for project execution 29
3.3 Procedure 30
3.4 Proposed Budget 30
3.5 Work plan 31
CHAPTER FOUR 32
DATA ANALYSIS, RESULTS AND DISCUSSION 32
4.1 Galvanized steel vortex 32
4.1.1 Advantages of galvanized steel 32
3. Rust resistance 32
4.1.2 Assembly 33
4.2 Plastic vortex 37
4.2.1 Plastic 37
4.2.2 Equipment 38
4.2.3 Assembly 39
4.3 Panning and the amalgamation process 47
4.4 Vortex Machine Process 48
4.4.1 Data Collection process 48
4.5 Results 51
4.6 Sources of Error 51
CONCLUSION 52
RECOMMENDATIONS 53
REFERENCES 54
LIST OF FIGURES
Figure 1: A Google Map Visual Representation of Migori, Kenya 11
Figure 2: The geological map of the Migori Gold Belt showing different types of rocks that host gold 12
Figure 3: Gold Size Classification: The new international nomenclature for gold size as presented by members of the Alaska Gold Forum. 14
Figure 4: Global sources of Mercury 18
Figure 5: A Picture illustrating centripetal and centrifugal forces on a particle 20
Figure 6: Surface profile of free vortex flow 22
Figure 7: Velocity profile of free vortex flow 22
Figure 8: A pie chart representing results in table 2 27
Figure 9: A pie chart representing results from table 4 28
Figure 10: A visual representation of the work plan 31
Figure 13: Image of Galvanized Steel Vortex 36
Figure 14: Image of Galvanized Steel Vortex and Galvanized steel bucket 36
Figure 15: Polyethylene and polypropylene chemical structure. 37
Figure 16: 2D drawing of the plastic vortex with dimensions in millimeters 40
Figure 17: 3D design of the plastic vortex 40
Figure 18: Plastic Vortex machine 41
Figure 19: Bucket with drilled holes for overflow 41
Figure 20: An image of PPR fittings, gate valve, hose pipe, sump pump and jubilee clips 42
Figure 21: A cracked plastic vortex fixed using sand and super glue 43
Figure 22: An Image of the cone attached to the basin using sand and glue 44
Figure 23: Silica gel used to smoothen out the cone edges 44
Figure 24: Side view of the vortex 46
Figure 25: Top view of the vortex setup. 46
LIST OF TABLES
Table 1: Scientific properties of gold 16
Table 2: Responses to the alternatives of gold extraction methods 26
Table 3: Responses on the vortex machine increasing gold concentration 27
Table 4: A table representation of the estimated budget 30
Table 5: A table representing the components of the galvanized steel vortex 34
Table 6: plastic vortex components 38
Table 7 : Vortex model comparison table 45
Table 8: Data collection sheet 47
Table 9: A table showing the chemical composition of the ore sample 48
Table 10: Test runs after primary crusher using jaw crusher 49
Table 11:Test runs after further secondary crushing in the ball mill 50
Table 12:A comparison of the final results 51
ABSTRACT
Artisanal and small-scale mining (ASM) is a collective term covering formal and informal mining which is characterized by low capital investment and relatively simple methods for exploration, extraction, and processing (Council, 2020).
Migori county, which lies in the south-western part of Kenya in sub-Sahara Africa as a growing population artisanal small-scale miners in the area due to the gold present in the area and the general shift to non-agricultural based activities. The majority of the population is poverty-stricken and living in rural areas such as Mikei, the area of study of this project. According to the International Monetary Fund, the informal economies in the sub-Sahara contribute between 25 - 65% of the Gross Domestic Product (GDP) and accounts for between 30-90% of total non-agricultural employment (Fund (IMF), 2017)
This project aims at introducing an alternative fine gold concentration method by customizing the already existing blue-bowl vortex machine, to replace the panning method of recovering fine old by making it more accessible and affordable to ASGM miners in the processing tail-end of the concentration process. Using engineering design principles, a model will be fabricated using locally available materials and customized to meet the specific needs of ASM miners which include, and not limited to increasing the percentage of gold recovered, reducing the labor input required and meet the rising global demand to phase-out and eventually eliminate mercury inline objectives of the Minamata convention of 2013 and the Sustainable Development Goals adopted by the United Nations in 2015 in which Kenya is a signatory of both.
Keywords: ASGM, Fine gold, concentration, vortex machine
CHAPTER ONE
INTRODUCTION
Background
Gold in Migori was discovered in 1920 and by 1927 about 100kg of gold had been recovered. This led to the discovery of new gold deposits and exploitation by various mining companies. Large scale mining operations came to a halt, shortly after Kenya's independence and artisan miners have been the sole producers of gold in the belt (Ogolla, 2014).
Artisanal Small-Scale Mining (ASGM) in Migori district involves both open-cut and underground operations. Generally, after liberation, they use the amalgamation method, which is the process of extracting gold particles by mercury and forming amalgam (Au - Hg). The process is simple and inexpensive but due to the use of heavy metals, it is hazardous to the environment and a threat to the health of the miner and the community as a whole. The concentrations of heavy metals, mainly mercury and lead in the Migori district are above acceptable levels that is, above 722ppm (Revis, 1990)with the highest levels of toxic metal contamination recorded in sediments; Mikei tailings 1920ppm.
Also, ASGM miners use traditional sluices that often recover gold particles greater than 1mm which is only 20% of the gold (Grayson, 2007).
The incorporation of gravity-based methods such as vortex machines, shaking tables, and centrifuges to artisanal miners will increase the recovery of gold and provide a safer and less labor-intensive alternative to the use of mercury. Based on the specific gravity and grain size of gold, the project aims to incorporate a gravity concentration technique hence increasing fine gold recovery.
Study Area
Migori is a county located in the former Nyanza province. It is 0.9366 degrees south of the equator and 34.4198 degrees east in longitude
[Show More]
, 1e by Cristiane Surbeck, Jeff Kuo.png)
, 1e by Fariborz Tayyari.png)
