Sluice Box Research Articles

Efficiency of sluice boxes in precious metal placer mining

Efficiency of sluice boxes in precious metal placer mining

Investigating Optimal Angle of Inclination of a Sluice Box for Improved Artisanal Gold Recovery in Batouri, Cameroon

Investigating Optimal Angle of Inclination of a Sluice Box for Improved Artisanal Gold Recovery in Batouri, Cameroon

Program for determination of zones of gold concentration on sluices of washing devices

Currently sluice washing devices are the most common in alluvial gold mining. Their use provides a sufficiently high performance, relatively low power consumption, and acceptable recovery of valuable components. The theoretical provisions of traditional hydraulics make it possible to determine all the main parameters of the movement of particles of rocks and gold in the pulp, however, in real operating conditions of the sluice box, their actual values will differ greatly from the calculated ones, especially if there are solid fractions in the pulp with a particle size of more than 20 mm. This is explained by significant fluctuations in the values of the surface, average and bottom velocities of the two-phase flow, vertical pulsation velocity in conditions of constrained movement of the different fractional composition of rocks. The article presents the results of experimental studies to identify the dependence of the distance traveled by an individual gold particle and host rocks in a two-phase flow through a sluice, the bottom of which is lined with trapping coatings, on the design and technological parameters of the flushing device. The mathematical model for determining this distance formed the basis of the Gold Enriching program. The program allows, in a wide range of initial data, to determine the zones of concentration of gold of a certain size at the sluice boxes.

Assessment of surface water quality and mercury levels from Artisanal and small-scale gold mining (ASGM) along Acupan River, Benguet, Philippines.

Artisanal and small-scale mining activities are most evident among communities surrounding the Acupan River in Itogon Benguet. The mining activities include manual extraction of gold ores, use of improvised ball/rod mills and sluice boxes, and metallurgical processing such as cyanidation, carbon-in-pulp (CIP) and amalgamation. This study evaluates the influence of small-scale mining and the geology/mineralization of the Acupan Au-Ag-Te deposit to the water quality of the Acupan River and to the possible human exposures to Hg within the small-scale mining community. Different water quality parameters were monitored along selected sites along the Acupan River for a year and the results showed that the low average values of dissolve oxygen (DO) (2.54-4.53mg L-1) and the relatively high average values of pH (8.84-10.10), sulfate (300.00-1133.33mg L-1), nitrate (11.33-134.67mg L-1), arsenic (As) (0.227-0.574mg L-1) and mercury (Hg) (0.004-0.054mg L-1) have exceeded the acceptable criteria limit of the Department of Environment and Natural Resources for Class C waters. The exceeded values are noted to occur in areas where extensive small-scale mining activities are being done and have affected as well the downstream areas. To test possible human contamination in the use of Hg, hair samples from 56 volunteers were analyzed for total Hg (T-Hg) following standard protocols. The T-Hg concentrations in hair samples are mostly inorganic and are determined in various parameters such as sex, geographic location, occupation, age, fish consumption and localization in hair. Though not significantly different, higher Hg values are noted in males (1.280 ± 0.446ngmg-1) than among females (0.651 ± 0.163ngmg-1) as well as those with ages 41-50years (3.130 ± 2.330ngmg-1) as compared to other age groups. The higher amounts of inorganic Hg in human hairs could be attributed to the discrete yet prevalent use of amalgamation. The findings of this study emphasize the need for better regulations of the small-scale mining activities and for stricter implementation of the total ban on the use of Hg in ore processing to ensure better water quality of Acupan River as well as the health and safety of the communities surrounding the river.

Investigating the Potentials of Sluice Box Angle of Tilt on the Beneficiation of Birnin-Gwari Gold Deposit

The potentials of sluice box angle of tilt on the beneficiation of Birin-Gwari gold deposit was investigated. The sample was sourced from twenty (20) pits on the mine site and homogenized towards chemical characterization. Particle size analysis using 100 g head sample over the sieve range of 500 µm and 45 µm. 100 g each of the homogenized samples was charged into the sluice box at varied tilt angles ranging from 10º to 60º and also at a varying feed rate of 50 kg/hr to 100 kg/hr at 1000 mls flow rate. The Energy Dispersive X-ray Fluorescence Spectrometry (ED-XRFS) revealed 10.15 ppm Au, 0.43% Fe, 0.05% Pb, and other constituent elements in trace form. Particle size analysis showed the liberation size to be -125+90 µm. The highest yield in mass was given as 32.70 g assaying 43.20 ppm at an angle of 10º and varied feed rate while keeping other parameters/constituent constant and also, 56.32 g was the highest yield in mass assaying 12.83 ppm at 50 kg/hr feed rate.Keywords: Birnin-Gwari gold, Beneficiation, Characterization, Sluice box.

Automated Gold Grain Counting. Part 1: Why Counts Matter!

The quantitative and qualitative assessment of gold grains from samples of glacial till is a well-established method for exploring gold deposits hidden under glaciated cover. This method, which is widely used in the industry and has resulted in numerous successes in locating gold deposits in glaciated terrain, is still based on artisanal gravity separation techniques and visual identification. However, being artisanal, it is limited by inconsistent recoveries and difficulties associated with visually identifying the predominantly small gold grains. These limitations hinder its capacity to decipher subtle or complex signals. To improve detection limits through the recovery of small gold grains, a new approach has recently been introduced into the industry, which is commercially referred to as the “ARTGold” procedure. This procedure involves the use of an optimized miniature sluice box coupled with an automated scanning electron microscopy routine. The capabilities of this improved method were highlighted in this study by comparing till surveys conducted around the Borden gold deposit (Ontario, Canada) using the conventional and improved methods at both local and regional scales. Relative to that with the conventional approach, the improved method increased the recovery of gold grains from samples (regional and down-ice mineralization) by almost one order of magnitude. (regional and down-ice mineralization), dominantly in regard of the small size fractions. Increasing the counts in low-abundance regional samples allows for a better discrimination between background signals and significant dispersions. The described method offers an alternative for improving the characterization of gold dispersal in glaciated terrain and related gold deposit footprints.

Advances in Saltmarsh Restoration

An innovative method applicable to saltmarsh habitat restoration using dredged sediment was tested. Biodegradable wooden sluice boxes were placed in eroded “pits” or pools in the damaged saltmarsh and dredged sediment was pumped to fill these pits up to the level suitable for saltmarsh flora colonisation. The sluice boxes were used to carefully control volumes and dewatering of dredged material to maximise the resultant fill level. Sediment was left to settle during periods of high tide and water was prevented from entering and mixing the deposited sludge. During low tide, the supernatant was drained off, enabling more material to be deposited. This technique helped develop a layer of substrate for pioneer halophytes to colonise, without loss of material through natural entrainment and deposition back into source sites. Increases in colonisation, consolidation, shear strength and bulk density of the newly placed sediment proved the suitability of this technique for habitat restoration.

Estimation of operating costs and energy consumption in beneficiation of alluvial gold deposits

There are many scientific and practical works related to the identification and assessment of factors affecting the efficiency of beneficiation of placer sands at the sluice box, while the energy consumption of the beneficiation process, as well as assessing the efficiency of the sand screening process and the cost of maintaining the devices, is given little attention. Studies of the energy consumption of sand washing, carried out at several alluvial deposits, made it possible to identify the most energyconsuming devices, as well as to compare the energy expended for transporting rock through processing plants and to provide solid to liquid ratio during beneficiation at sluice boxes.

Improving fine gold recovery in sluice boxes

Improving fine gold recovery in sluice boxes

Pengaruh Riffles dan Kemiringan Underflow Sluice Box Terhadap Optimalisasi Pemisahan Bijih Timah Skala Laboratorium

Underflow sluice box is a mineral processing tool that aims to separate the main minerals from associated minerals based on the principle of gravity concentration, which is equipped with boil boxes and underflow riffles as a separation medium in tin ore. The use of laboratory scale underflow sluice box provides Sn concentrate results with high Sn grade and recovery through the influence of underflow riffles and slope positions. Where underflow riffles parameters are in the position of 0.5 cm, 1 cm and 1.5 cm and the slope used is 0 °, 3 ° and 5 °, the experiment is carried out 9 times using 2 kg feed and the same Sn grade in each sample. From the results of the experiment obtained the dry weight and Sn grade concentrates which were analyzed by Sn grade using Grain Counting Analysis (GCA) and recovery calculations. After analysis and calculation, the highest Sn grade was found in sample 9 with underflow riffles position of 1.5 cm, slope of 5 ° and water flow velocity in the water flow velocity at 54 l/minute at 44.61 %, while recovery was highest in sample 3 with underflow riffles 1.5 cm, slope of 0 ° and water flow velocity in the water discharge at 54 l/minute at 99.13 %. Based on these results it can be said that if the underflow riffles and slope position is greater, the recovery and Sn grade concentrates are obtained high and if the underflow riffles and slope positions are smaller, the recovery is high with a low Sn grade concentrates.

Mercuric pollution of surface water, superficial sediments, Nile tilapia (Oreochromis nilotica Linnaeus 1758 [Cichlidae]) and yams (Dioscorea alata) in auriferous areas of Namukombe stream, Syanyonja, Busia, Uganda.

The mercury content and the contamination characteristics of water, sediments, edible muscles of a non-piscivorous fish (Oreochromis nilotica Linnaeus 1758 [Cichlidae]) and yams (Dioscorea alata) from Namukombe stream in Busia gold district of Uganda were evaluated. Human health risk assessment from consumption of contaminated fish and yams as well as contact with contaminated sediments from the stream were performed. Forty-eight (48) samples of water (n = 12), sediments (n = 12), fish (n = 12) and yams (n = 12) were taken at intervals of 10 m from three gold recovery sites located at up, middle and down sluices of the stream and analyzed for total mercury (THg) using US EPA method 1631. Results (presented as means ± standard deviations) showed that water in the stream is polluted with mercury in the range of < detection limit to 1.21 ± 0.040 mg/L while sediments contain mean THg from < detection limit to 0.14 ± 0.040 ugg−1. Mean THg content of the edible muscles of O. nilotica ranged from < detection limit to 0.11 ± 0.014 ugg−1while D. alata contained from < detection limit to 0.30 ± 0.173 ugg−1mean THg. The estimated daily intake ranged from 0.0049 ugg−1day−1 to 0.0183 ugg−1day−1 and 0.0200 ugg−1day−1 to 0.0730 ugg−1day−1 for fish consumed by adults and children respectively. The corresponding health risk indices ranged from 0.0123 to 0.0458 and 0.0500 to 0.1830. Estimated daily intake was from 0.0042 ugg−1day−1 to 0.1279 ugg−1day−1 and 0.0130 ugg−1day−1 to 0.3940 ugg−1day−1 for D. alata consumed by adults and children respectively. The health risk indices recorded were from 0.011 to 0.320 and 0.033 to 0.985 for adults and children respectively. The mean THg content of the sediments, edible muscles of O. nilotica and D. alata were within acceptable WHO/US EPA limits. About 91.7% of the water samples had mean THg above US EPA maximum permissible limit for mercury in drinking water. Consumption of D. alata grown within 5 m radius up sluice of Namukombe stream may pose deleterious health risks as reflected by the health risk index of 0.985 being very close to one. From the pollution and risk assessments, mercury use should be delimited in Syanyonja artisanal gold mining areas. A solution to abolish mercury-based gold mining in the area needs to be sought as soon as possible to avert the accentuating health, economic and ecological disaster arising from the continuous discharge of mercury into the surrounding areas. Other mercury-free gold recovering methods such as use of borax, sluice boxes and direct panning should be encouraged. Waste management system for contaminated wastewater, used mercury bottles and tailings should be centralized.

Magnetic separation applications in the final treatment of sluice box concentrates

Magnetic separation applications in the final treatment of sluice box concentrates

A preliminary study on the characteristics of the tailing ofthe hammermill –sluice box operation at the kraboedoin and kriki negi hill District brokopondo- Suriname

The small scale mining in Suriname is one of the most important livelihoods and biggest contributors to the economy of Suriname. However this sector needs to be evaluated continuously in order to introduce environmental friendly and more efficient methods. Another pre condition before introducing other environmental friendly and more efficient method is; knowing the compound of the ore. The Hammer mill – Sluice box method is one of the most used methods by the small scale miners. This technique uses a Hammer mill to grind the ore and a Sluice box to concentrate the gold.To study some charactistics of the tailing of the small scale gold miners at Kraboedoin and Kriki negi hills, the tailing samples were collected. The particle size distribution, the gold content and the heavy mineral percentage per fraction of these samples were determined and analyzed.The results of both sites showed that about 70% of the tailing had size between 0.250mm and 2.000mm, the average gold content in the tailing at Kraboedoin hill is 0.93ppm and at Kriki negi hillis 3.30ppm.

Rebellious Gold Extraction from Gravity Concentrates and Placer Tailings by Chemical Reagents

When gold occurs in mining waste for a long time, it becomes coated with dense films of hydroxide of iron, manganese, copper and silver sulfides, hydromica powder and clayey particles, which greatly complicate concentration of such gold by gravity. An efficient method to remove such coatings from gold is treatment of waste using chemical reagents based on halogen-containing compounds. The article presents experimental results on extraction of fine gold from tailings of sluice boxes and dredging classifiers using such chemical reagents.

The Occurrence and Characteristics of Gold Nuggets and Masses

THE COMMON IMAGE OF A GOLD NUGGET is that of a rounded piece of gold just plucked from a pan or a sluice box. Implied in that image is some limiting minimum size and a history of transport, usually...

Interpretation of Hand Tool Movement's Trajectories by Spatial Analysis of Bronze Age Tool Marks

The Bronze Age timber construction methods and carpentry techniques can only be studied in unique cases as the ancient wooden artefacts are rarely preserved in good conditions. On the other hand, few archaeological finds as the sluice box from Mitterberg, Austria offer novel interpretation opportunities since the spatial analysis of hand tool impressions results additional information about the utilized hand tool characteristics and about the woodworking processes. An experimental survey was carried out for the better understanding of the tool mark based impact angle investigations of various hand tool strikes. The fine longitudinal morphological parameters of the unknown hand tool heads have also been studied through additional materials as e.g. technical drawings. The combination of the different slope values at the facet outsets and at the adze heads describe the geometry attributes of the unknown impact strikes and these values must be between 25–30 degrees. The trajectory calculations could be achieved by the results of the experimental survey as synchronized stereo pairs were oriented and used to reconstruct the steps of the hand tool movements. Furthermore, the potential trajectories of the Bronze Age adze were interpreted from the impact angles and these results were simulated and visualized with the suggested hand tool handle positions in CAD environment.

English

The Ute Ulay Mining complex, located approximately five miles west of Lake City, CO is an inactive Ag, Au, and Zn mining/milling operation that operated from the 1880's until the 1970's, and sporadically into the mid 1990's. During operation, milled tailings were pumped upstream from the mine/mill site in a sluice box and deposited into five tailings impoundments. The tailings impoundments comprised 13,000 yd 3 , on 6 acres of public lands managed by the Bureau of Land Management (BLM). Prior to reclamation, windblown tailings from the impoundments exposed the public to potentially harmful dust, the tailings from the lowest pond washed into Henson Creek during high flow, and Zn, Pb and Cd leached into groundwater through the unlined tailings ponds. The objective of the reclamation was to mitigate the risk of human exposure to air- borne dust, and to protect surface and groundwater sources from further contamination from the tailings impoundments. Reclamation of the mine and mill waste materials was completed using cementatious paste technology. All waste materials were screened and separated on-site, and the fine-grained waste materials were mixed with cement and water to form the paste. The repository was constructed using a layered design, with paste forming the base and cap, and coarse waste materials placed as a middle layer within the enclosing paste. Following repository completion, the site was graded, drainage channels were constructed, groundwater-monitoring wells were installed, and six acres were revegetated. Reclamation was completed in October, 2009, with maintenance in 2011. Following three growing seasons, the vegetation community is healthy, with minimal weedy species, and no noxious weeds. The surface water quality in Henson Creek indicates a slight reduction in Zn and Cd levels, and other metal concentrations in the groundwater have declined by over an order of magnitude.

Optimization of flushing sluice flow in hydrohoist gold washing machines

The lab and commercial tests have validated basic parameters of flow at locks of high capacity sluice box with riffles. The found relations between the Darcy coefficient, Reynolds numbers and Froude numbers allow obtaining balanced design and technology parameters for industrial sluice boxes of the type of PGSH-II-50.

GIS-BASED SURFACE ANALYSIS OF ARCHAEOLOGICAL FINDS

Abstract. The international research project HiMAT (History of Mining Activities in the Tyrol and adjacent areas) is dedicated to the study of mining history in the Eastern Alps by various scientific disciplines. The aim of this program is the analysis of the mining activities’ impacts on environment and human societies. Unfortunately, there is only a limited number of specific regions (e.g. Mitterberg) to offer possibilities to investigate the former mining expansions. Within this multidisciplinary project, the archaeological sites and finds are analyzed by the Surveying and Geoinformation Unit at the University of Innsbruck. This paper shows data fusion of different surveying and post-processing methods to achieve a photo-realistic digital 3D model of one of these most important finds, the Bronze Age sluice box from the Mitterberg. The applied workflow consists of four steps: 1. Point cloud processing, 2. Meshing of the point clouds and editing of the models, 3. Image orientation, bundle and image adjustment, 4. Model texturing. In addition, a short range laser scanning survey was organized before the conservation process of this wooden find. More accurate research opportunities were offered after this detailed documentation of the sluice box, for example the reconstruction of the broken parts and the surface analysis of this archaeological object were implemented using these high-resolution datasets. In conclusion, various unperceived patterns of the wooden boards were visualized by the GIS-based tool marks investigation.

HYDROLOGIC AND FEATURE-BASED SURFACE ANALYSIS FOR TOOL MARK INVESTIGATION ON ARCHAEOLOGICAL FINDS

Abstract. The improvement of detailed surface documentation methods provides unique tool mark-study opportunities in the field of archaeological researches. One of these data collection techniques is short-range laser scanning, which creates a digital copy of the object’s morphological characteristics from high-resolution datasets. The aim of our work was the accurate documentation of a Bronze Age sluice box from Mitterberg, Austria with a spatial resolution of 0.2 mm. Furthermore, the investigation of the entirely preserved tool marks on the surface of this archaeological find was also accomplished by these datasets. The methodology of this tool mark-study can be summarized in the following way: At first, a local hydrologic analysis has been applied to separate the various patterns of tools on the finds’ surface. As a result, the XYZ coordinates of the special points, which represent the edge lines of the sliding tool marks, were calculated by buffer operations in a GIS environment. During the second part of the workflow, these edge points were utilized to manually clip the triangle meshes of these patterns in reverse engineering software. Finally, circle features were generated and analysed to determine the different sections along these sliding tool marks. In conclusion, the movement of the hand tool could be reproduced by the spatial analysis of the created features, since the horizontal and vertical position of the defined circle centre points indicated the various phases of the movements. This research shows an exact workflow to determine the fine morphological structures on the surface of the archaeological find.