데이터셋 상세
캐나다
Gold Losses at Klondike Placer Mines - Gold Recovery Project (Phase 1)
Placer mining has made significant contributions to both the history and lifestyle of the Yukon and continues to provide a stable non-governmental economic force. This year there are approximately 185 active placer mining operations with a combined reported contribution in excess of $65 million to the Yukon's small resource based economy. Placer gold recovery at many of these operations is not optimized due to a lack of access to current technology, training and testing facilities. Current gold recovery technology is almost exclusively confined to sluice boxes. A limited number of operations additionally employ feeders and screens. Sluice boxes are very simple, reliable, inexpensive, and yield very high concentration ratios. Many factors contribute to improved recoveries with a sluice box including: a) Controlled feed rates at less than 8 loose cubic yards/hr per foot of sluice width; b) screened pay gravels to at least 3/4 of an inch; c) adequate washing and liberation of free gold particles; d) water ratio of 17 Imperial gallons/minute per loose cubic yard of pay gravels/hr; e) use of both expanded metal and Hungarian riffles in every sluice run; f) utilization of a slick plate section before a riffle section to allow gold segregation in the slurry; g) even feeding through automation or strict manual control of loading equipment; h) sluice box gradients of between 1.5 and 2 inches/foot; and i) frequent removal of sluicebox concentrates for upgrading. Suiceboxes can recover up to 95% of gold particles as fine as 150 mesh provided that the precious conditions are realized. Sluiceboxes may not be adequate for placer deposits containing very fine pay gravel with abundant clay and fine silt, a high proportion of high density minerals, or extrememly fine (-150 mesh) or flattened gold particles. For a White Channel deposit, an oscillating sluicebox kept riffles from packing and provided reasonable gold recovery. Sampling design is critical for placer gold testwork because test results can be distorted by the "nugget" effect. The uneven distribution of gold particles in a placer deposit often produces large random sampling errors. A sluice tailings stream represents one of the easiest sampling locations, provided the samples are caught in the air. Sluice tailings samples were collected from six operating Yukon mines at regular intervals with hand held buckets, sample cutters, or a large steel box depending on the coarseness of the discharge. The samples which represented between 1.5 and 7 loose cubic yards, were screened at 16 mesh and shipped to a tabling facility. At each site, a large number of sample increments were alternately stored in two containers as interpenetrating samples over a period of 2 to 4 days. Comparison of these two samples indicated relative standard deviations (coefficient of variation) as low as 8%.These errors soared 56% (nugget effect) for two sites with high losses, when a limited number of gold particles as coarse as 14 mesh were found in their tailings. To evaluate gold recovery efficiency, the collection of head samples is an impratical task as well as being of dubious value. At each operation, the sluice boxes were cleaned directly before and after the sampling period. A calculated head grade was determined by adding the gold recovered in the sluicebox and the gold lost to the tailings. The placer gold data recorded over the 2 to 4 day sampling periods represent only a snapshot of a total deposit's characteristics.
데이터 정보
연관 데이터
Particle-size distribution of gold within the Sulphur and Dominion creek drainages, Klondike District, Yukon, and implications for gold winning and the formation of distal placers containing fine gold
공공데이터포털
A reduced efficiency of gold recovery with decreasing particle size using a sluice box raises the possibility of a very fine gold resource within the Klondike. The grade of fine gold within gravel recovered from the southern Klondike was assessed using a combination of screening and bulk leaching by cyanidation. This approach eliminates the nugget effect and size ranges selected correspond to particle sizes exploitable by different metallurgical methods: <53 µm (cyanidation), 53-125 µm (‘enhanced g’ concentrators), 125-500 µm (sluice boxes). Colluvium, virgin gravel and tailings from various mining operations were collected from a relatively long drainage where accumulation of fine gold could feasibly occur. In all samples, gold <125 µm was negligible. Despite this negative result, this approach to resource evaluation is straightforward and could be applied advantageously in other areas where source mineralization contains fine gold. A distinction should be made between placer gold grains of fine but equant nature derived from proximal mineralization and gold rendered fine and flaky by fluvial transport.
Yukon hard rock mining, development and exploration overview 2019
공공데이터포털
Yukon mineral exploration activity dipped slightly in 2019. Exploration expenditures were approximately $105 million, compared to $120 million in 2018. Development expenditures are estimated at $240 million, primarily for the development of Victoria Gold Corp.’s Eagle mine ($183M), and, to a lesser extent the advancement of Newmont Goldcorp.’s Coffee gold project and the reopening of the Minto gold-copper-silver mine by Pembridge Resources. Production dollars are attributable to operations at Victoria Gold’s new Eagle mine and the newly reopened Minto mine of Pembridge Resources plc. The number of active exploration projects dropped significantly from 155 projects in 2018 to 80 projects in 2019. To some degree, this reflects the continuing tight equity markets. Thirty-six of the 80 projects spent more than $1M, while 44 projects spent less than $500,000. The majority of smaller projects received Yukon Mineral Exploration Program (YMEP) grant funding. In terms of all Yukon projects, gold continues to be the most sought-after commodity, with 68% of the projects targeting it. The remainder of projects focused on exploring for lead-zinc, copper, silver, or nickel-PGEs, and to a lesser extent, tin, cobalt or vanadium. Claim staking in 2019 was down significantly over the previous year to 2212 claims. The number of claims in good standing is 173,161, down from an all-time high of 252,902 in 2012. Drilling numbers were down slightly. Total drilling in 2019 was 221,596 m, compared to 246,282 m in 2018.
The Stewart River placer project, west-central Yukon
공공데이터포털
The Stewart River map area (115 O&N) is the most important historic and current placer gold producing region in the Yukon. Unfortunately, the historic placer-gold deposits are becoming depleted, and more efficient mining of existing deposits and exploration for new deposits must be encouraged. Although placer deposits in the Klondike district are well described and their origin is quite well understood, placer deposits in the remaining part of the Stewart River map area have not been so well documented. The purpose of the Stewart River placer project is to describe and document the geology of known placer deposits, to interpret the formation of the placer deposits, and to relate the geology of the placer deposits to the regional surficial and bedrock geology. The objectives of the project are to aid in the exploration and mining of placer deposits by providing a comprehensive and up-to-date placer geoscience database. The utility of the placer database is that it can be used to construct placer deposit models (general summaries of given placer settings). These models then serve as predictors for future placer exploration and mining. Fieldwork for the project began in 1998 and will be completed in 2001; results of the project will be published in a final report and a resource appraisal map for placer gold.
Selected excerpts from placer gold recovery research
공공데이터포털
The highest percentage gold recoveries occurred at mines which screened their feed to minus one inch, used both expanded metal and angle iron riffles on top of nomad matting for every sluice run and fed their runs at recommended feed and water rates. Expanded metal riffles are efficient at recovering placer gold particles finer than 1 mm while angle iron riffles are more efficient at recovering those greater than 1 mm. Slick plates allow gold particles to segregate to the bottom of the pay gravel slurry where they are more readily available for recovery by the riffles. Additional field testing of existing placer operations should be conducted to expand the knowledge of gold recovery at a greater variety of deposit types and recovery equipment such as hydraulic riffles.
Yukon placer mining 2023 development and exploration overview
공공데이터포털
Placer districts across the Yukon yielded strong production this season as a result of favourable conditions. A continued rise in gold prices and stable fuel prices were complemented by mild temperatures that allowed for an extended sluicing season. As of November 10, 2023, the 146 active placer operations in the Yukon had collectively generated $143.7M in production revenue. The Dawson Mining District was the primary contributor to gold production, accounting for 89% of the total production for the Yukon. The Mayo Mining District followed with a 7% contribution and Whitehorse Mining District reported 4% of the overall production.
A review of placer gold concentrate recovery and upgrade options
공공데이터포털
In 2010-11, Yukon Geological Survey awarded a contract to NEW ERA Engineering Corporation of Whitehorse to undertake a study of recent developments in gravity gold recovery techniques. In partial fulfillment of the contract, Randy Clarkson attended the Gravity Gold 2010 Optimizing Recovery Conference in Ballarat, Australia, and presented the following report and recommendations at the Yukon Placer Workshop in November 2010.
An Evaluation of the Gold Recovery of Placer Drills Using Radio Tracers
공공데이터포털
In the last five years, eroding gold prices, increasing production costs and the depletion of reserves have resulted in a dramatic increase in the use of drilling to evaluate placer deposits. Accurate sampling and deposit evaluation would enable planning for cost-effective mining and reclamation. However, sampling placer gravel accurately is an extremely difficult task due to the nugget effect (inclusion or loss of a single particle of gold) and any errors are compounded by the small size of the drill samples. Additional sampling errors result from contamination, splitting and fire assaying. More placer mine failures can be attributed directly to improper sampling and sample processing practices during property evaluation than to any other cause. There is very little impartial, accurate information available to guide the selection of modern drills. Drillers and their equipment are often selected for their penetration rate or cost-per-foot rather than for sampling accuracy or gold recovery. A brief description of several types of drills including churn, auger, rotary tricone, reverse circulation, Becker hammer, down-the-hole hammer and Sonic drills is summarized in Section 6 from references. Three solid auger drills and two types of reverse circulation (R/C) drills were evaluated under typical Yukon field conditions using radioactive placer gold as tracers (radiotracers). A frozen cylindrical core of compacted gravel containing four sizes (-10+14, -20+28, -35+48 and -65+100 mesh) of radiotracers was placed in 35 drill holes and the holes were redrilled. Hand-held scintillometers were used to track gold losses during drilling, sample recovery and sample processing. Radiotracers lost due to spillage and blow-by around the collar (top) of the hole, and those trapped in drilling equipment (carry-over) were easily located. The results of these tests are summarized Table 1. There was no significant difference between the recovery of the four sizes of gold particles with any of the reverse circulation or auger drills tested. Observations and down-hole scintillometer records indicate that the radiotracers did not follow the bit down the hole and were either carried out of the hole or forced onto the sides of the hole at or above the depth at which the radiotracer core was positioned.
An Evaluation of the Gold Recovery of Placer Drills Using Radio Tracers (Part II)
공공데이터포털
In the last five years, eroding gold prices, increasing production costs and the depletion of reserves have resulted in a dramatic increase in the use of drilling to evaluate placer deposits. Accurate sampling and deposit evaluation would enable planning for cost-effective mining and reclamation. However, sampling placer gravel accurately is an extremely difficult task due to the nugget effect (inclusion or loss of a single particle of gold) and any errors are compounded by the small size of the drill samples. Additional sampling errors result from contamination, splitting and fire assaying. More placer mine failures can be attributed directly to improper sampling and sample processing practices during property evaluation than to any other cause. There is very little impartial, accurate information available to guide the selection of modern drills. Drillers and their equipment are often selected for their penetration rate or cost-per-foot rather than for sampling accuracy or gold recovery. A brief description of several types of drills including churn, auger, rotary tricone, reverse circulation, Becker hammer, down-the-hole hammer and Sonic drills is summarized in Section 6 from references. Three solid auger drills, two types of fully cased normal circulation (N/C) drills and two types of reverse circulation (R/C) drills were evaluated under typical Yukon field conditions using radioactive placer gold as tracers (radiotracers). A frozen cylindrical core of compacted gravel containing four sizes (1.2-1.7, 0.60-0.84, 0.3-0.42 and 0.15-0.21 mm) (-10+14, -20+28, -35+48 and -65+100 mesh) of radiotracers was placed in 44 drill holes and the holes were redrilled. Hand-held scintillometres were used to track gold losses during drilling, sample recovery and sample processing. Radiotracers lost due to spillage and blow-by around the collar (top) of the hole, and those trapped in drilling equipment (carry-over) were easily located. The results of these tests are summarized Table 1. There was no significant difference between the recovery of the four sizes of gold particles with any of the fully cased nomal circulation, reverse circulation or auger drills tested. Observations and down-hole scintillometre records indicate that the radiotracers did not follow the bit down the hole and were either carried out of the hole or forced onto to the sides of the hole at or above the depth at which the radiotracer core was positioned.
Yukon Placer Mining Industry 2018 to 2020
공공데이터포털
The Yukon Placer Industry Report is a reflection of the strong working relationship between the Yukon Geological Survey (YGS) and the Yukon placer mining industry. Our annual tours into the various gold fields are always productive and provide new details on placer gold settings, which are encapsulated in this report.
Stewart River Placer Project, Resource Appraisal Map for Placer Gold in the Stewart River (115N/O) and part of the Dawson (116B/C) map areas, Yukon (1:250 000 scale)
공공데이터포털
not_specified
목록