This project was undertaken to evaluate the potential to economically recover additional metal values from the 4.6 million tons of Keno Hill flotation tailings which grades 3-4 oz/t silver, 0.8% lead and 0.9% zinc. The study determined that the higher grade portion of the tailing, containing some 1.0 million tons at 5.35 oz/t Ag, responds well to cyanide heap leaching with a silver recovery of 50-60%. The testing data suggests that heap leaching is economically feasible at the current silver price of $US5.50/ounce and a currency exchange rate of 1.35 in favour of the US dollar. The response to gravity and flotation concentration was poor.

A Geophysical Program was conducted at 5 groundwater monitoring wells on March 4, 2000 at the Faro Tailings Area, Rose Creek, Faro, Yukon under the auspices of the Yukon Government's Mine Research fund, DIAND Mineral Resources and Environment Canada by EBA Engineering Consultants Ltd. The EM39 geophysical instrument is able to measure the electrical conductivity of the ground within about 1 metre of the probe. The probe is a cylinder 3.6 cm in diameter and 1.6 m long. The probe is slowly lowered down a water well and as it is lowered, it measures the conductivity of the soils surrounding the well. As the probe is lowered, any changes in the electrical conductivity of the ground indicates either:: 1) changes in the levels of contaminants (metals like zinc in this case) in the ground, or; 2) changes in the type of soil - for example if there is sand and then a layer of clay or silt. In order to distinguish whether the change is due to 1) or 2) a gamma probe was also used. The gamma probe is also slowly lowered down the well and it only measures changes in the type of soil. By comparing the readings of the two probes, one can determine what vertical zones in the soil were being affected by changes in the levels of contaminants in the soil and the soil's groundwater.

Considerable research has been carried out into the reclamation and revegetation of disturbed lands in the Yukon, including operating and abandoned mines, and mineral exploration sites in the Yukon. Reclamation efforts on tailings have focused on methods to establish an initial vegetative cover on disturbed areas. Guidelines have been established by Kennedy (1993) and Hill et al. (1996) for the optimum mixtures of fertilizer and seeds (both agronomic and native varieties)¿. ¿.A relatively new and unique method of tailings processing and disposal that is being used at a few mines around the world is called dry stacking. This method of tailings disposal has the potential to provide many benefits to mining companies and affords numerous environment advantages that slurry deposits do not¿. ¿.The purpose of this proposed project was to research current practices in other jurisdictions and to examine the best approaches for encouraging vegetative establishment on dry stack tailings in norhtern environments, particularly for potential mine sites in the Yukon.

Placer mining occurs extensively in parts of the Yukon, denuding riparian zones and lining valley bottoms with mine tailings. Revegetation of tailings was examined at two placer mines near Mayo to determine the influence of environmental variables on the speed and direction of the natural process. Vegetation species density and frequency on various substrates were compared with: age, slope and aspect of the site, and pH, particle size distribution, moisture content and organic content of the soill. In central Yukon, tailings are first colonized by ruderal (weedy pioneer) species such as fireweed and members of the Compositae (dandelion) family. These are replaced by willow-dominated communities after nine years. Willow communities support many species characteristic of the adjacent undistrubed black spruce forest, suggesting that the placer succession is similar to that of riverbank environments in interior Alaska. Revegetation of the tailings proceeds at the same rate for the first twelve years as does that following natural disturbance. Of the environmental factors examined, only age and slope were, statistically, associated with rate of revegetation. Both the percent cover and the number of species at a site were inversely associated with slope, suggesting that reduction of slope angle enhances vegetation regeneration.

A copy of this thesis is available at the EMR library – QE390.W55 1995. This thesis is available online at https://doi.org/10.22215/etd/1995-02989.

In May 2003, the proposal for this project was submitted to the Mining Environment Research Group (MERG). At that time Nevada Pacific Gold Ltd. (NPG) was in charge of water treatment operations at the Elsa Property, the location for this project. Subsequent to approval of the MERG project, on June 11, 2003, NPG terminated its option to purchase the property, thereby dissolving its previously accepted responsibility to act as the agent of the Yukon Territorial Government (YTG) to maintain the water treatment systems and monitor effluent water quality at various locations of the property. As of June 11, 2003 YTG assumed direct responsibility for care and control of the site. YTG entered into a contribution agreement with the Nacho Nyak Dun Development Corporation (NND DC) to provide care and maintenance services. Access was retained by the NND DC to provide technical management of the project. ACG proceeded with MERG project activities, conducting desktop research and collecting baseline soil and water quality samples in July. On September 2, 2003 YTG was formally made aware that as a result of the July field inspection under MERG, ACG was of the opinion that the flow from the Galkeno Adit was likely reporting directly to fish bearing waters. Various Yukon and Federal Government Departments and agencies including the Department of Fisheries and Oceans, the Department of Environment, Water Resources, and Energy Mines and Resources met on September 5, 2003 to discuss the situation. As a result of the meeting, YTG decided to redirect the Galkeno 300 flow via pipeline into the forested dispersion area that it previously occupied.

The revegetation of northern tailings sites presents many challenges. By using plants, which are naturally adapted to both the tailings environment and northern climatic conditions, fewer amendments and intervention will be required. In 2003, vegetation growing on and off the tailings and soil at three Yukon Territory, Canada, mine sites (United Keno Hill, Mount Skukum, and Wellgreen) was assessed and soil samples were collected. Through Canonical Correspondence Analysis (CCA), a statistical program that assesses relationships between plant species and environmental variables, I found that these plant communities are largely governed by a chemical-nutrient gradient (heavy metals and nutrients) and a ground cover gradient (bare and exposed conditions compared with full ground cover). The native grass Deschampsia caespitosa L. Beauv. was found colonizing all three tailings sites and its presence was associated with low nutrients, high heavy metal levels, and exposed ground, but it was also a habitat generalist. Five Yukon populations of D. caespitosa, originating from mine and uncontaminated sites were tested hydroponically for their tolerance to elevated Ni, Zn, and Cd concentrations. Intrinsic multiple metal tolerance occurred in all populations. In revegetation field trials in the Yukon, I planted seeds and transplants of 7 populations of D. caespitosa under different treatments: i) untreated, ii) compost, iii) fertilizer, and iv) combined (compost and fertilizer). At all sites, during the two years of data collection, local and non-local populations, including those from non-contaminated sites were able to establish, grow, and reproduce, even in unamended tailings and despite successive hot and dry summers. D. caespitosa also acted as a nurse crop, facilitating invasion of plants from adjacent habitats. The short term results suggest that the inclusion of Deschampsia caespitosa as a nurse crop for the revegetation of these northern mine tailings sites will be beneficial.

In July 2009 we re-visited the re-vegetation experiments, which had been set up on tailings in the period 2003-2006. The three experimental sites are at Mount Skukum, United Keno and Wellgreen. The experiments consisted of either seeding the tailings with various populations of the tufted hair grass and/ or with stratified (cold temperature treated) seed of the shrub soapberry, or making transplants of the same two species. The treatments included the addition of compost from the City of Whitehorse, addition of fertilizer as 7:7:7 pellets, addition of organic matter as sheep manure, peat or woody debris from on site and, in the case of Wellgreen, a lime addition to overcome the strong acidity. The results are striking and illustrated in the Plates 1-15. Data of performance and flowering success are shown in the Tables, as are chemical analytical data in the Figures and Tables. Plots set up in 2003 provide a nucleus for effective re-vegetation, having survived for 6 years. The success of the seedings and transplants at Mount Skukum and United Keno was good, while that at Wellgreen was very poor. Wellgreen has suffered flooding with washing out of plots and washing out of the neutralizing lime. Nevertheless, in compost additions plots at Wellgreen, set up in 2005 and 2006, a small amount of re-vegetation and survival has occurred, especially in the wetter areas near the tailings pond.

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.

URL: https://geoscience.data.qld.gov.au/dataset/cr047854 EPM 14121, PROSPECT CREEK, PARTIAL RELINQUISHMENT REPORT FOR PERIOD 3/8/2005 TO 2/8/2007