.
Enter the email you signed up with and we'll email it to you.
Location: 159 km NE from Boise, Idaho, United States
13181 Highway 55PO Box 429DonnellyIdaho, United States83615
Stay on top of the latest gold discoveries. Examine the latest updates on drilling outcomes spanning various commodities.
Mining scale, mining and mill throughput capaciites.Full profiles of select mines and projects.
Shaft depth, mining scale, backfill type and mill throughput data.Full profiles of select mines and projects.
Equipment type, model, size and quantity.Full profiles of select mines and projects.
Camp size, mine location and contacts.Full profiles of select mines and projects.
Idaho Gold Resources Company LLC holds title to the Yellow Pine, Hangar Flats, and West End deposits, all of the patented mill sites and all of the unpatented federal lode mining claims and unpatented mill sites.
The Stibnite Project is situated along the eastern edge of the Idaho Batholith, on the western edge of the Thunder Mountain caldera complex and within the Central Idaho Mineral Belt.Large, north-south striking, steeply dipping fault structures exhibiting pronounced gouge and multiple stages of brecciation occur in the District and are often associated with east-west and northeast-southwest trending splays and dilatant structures. The Yellow Pine and Hangar Flats deposits are hosted primarily by intrusive phases of the Idaho Batholith along the Meadow Creek Fault Zone (MCFZ). The West End Deposit is hosted primarily by Neoproterozoic to Paleozoic carbonate and siliciclastic metasedimentary rocks of the Stibnite roof pendant along the West End Fault Zone (WEFZ).Mineralization and alteration in the District are associated with multiple hydrothermal alteration events occurring through the Paleocene and early Eocene epochs. Mineralization occurs in numerous locations throughout the District in medium- to coarse-grained, felsic to intermediate intrusive host rocks and typically occurs as disseminated replacement mineralization within structurally prepared dilatant zones or adjacent to district- and regional-scale fault zones. Mineralization also occurs in association with sheeted veins, stockworks, endoskarns, and complex polymictic breccias. In the metamorphosed sedimentary rocks, mineralization occurs in association with dense fracture zones in structurally prepared sites and as stratiform manto-style replacements in reactive carbonate and calcareous siltite and schist units, as well as in cross-cutting vein arrays, breccia veins and dikes, and jasperoids (quartz-replaced carbonates).Main-stage gold mineralization and associated potassic alteration typically occurs in structurally prepared zones in association with very fine-grained disseminated arsenical pyrite (FeS2) and, to a lesser extent, arsenopyrite (FeAsS), with gold almost exclusively in solid solution in these minerals. Antimony-tungsten mineralization is associated with silicification and brecciation resulting in stibnite (Sb2S3) veining and distinctive black matrix breccias within discrete structural zones. A later stage of mineralization crosscutting early disseminated styles and primarily effecting rocks of the Stibnite roof pendant is associated with epithermal quartz-adularia-carbonate veins. Carbonates, primarily iron-magnesium-rich calcite and ankerite, along with potassium-rich illite ("sericite") and to a lesser extent chlorite and smectite clays are common alteration assemblages peripheral to the pervasive potassium feldspar and sericite alteration in the cores of the intrusive hosted deposits or in late structural zones.Yellow Pine DepositMineralization in the Yellow Pine Deposit is structurally controlled and localized by the northerly striking MCFZ and by conjugate splay or cross structures. The deposit shows metal zonation with gold mineralization occurring throughout the deposit footprint, with antimony and tungsten primarily in the central and southern portions of the deposit. Most of the mineralization in the deposit occurs west of the MCFZ and east of the Hidden fault zone. The geometry, width and continuity of precious metals mineralization changes along strike in the deposit in conjunction with a bend in the MCFZ and its intersection with the Hidden fault zone. To the south, gold and antimony mineralization occur within a breccia zone of the MCFZ. The width of mineralization ranges from 80 ft to 165 ft, extends for over 800 ft along strike, and is open at depth in this area.In the central region of the deposit, between 1,188,200N and 1,189,600N, mineralization is broadly disseminated over a width of 500 ft east of the Hanging Wall fault and west of the post-mineralization Hennessey fault, except where Hennessey fault has offset the western part of the mineralization to the north. Gold and antimony mineralization in the central region of the deposit are bounded to the south by a complex fault network. The width of mineralization in the central area of the Yellow Pine deposit ranges from 165 ft to over 650 ft wide, over 1,400 ft of strike length and extends down dip over 1,200 ft.Mineralization in the northern Homestake area of the Yellow Pine deposit ranges from 80 to 150 ft thick and extends for over 800 ft along strike and down dip. Mineralization occurs as a tabular body in the hanging wall of the Hidden fault/Clark Tunnel structure. The tabular zone steepens to the west and is truncated to the west against the East Boundary fault, a gouge zone within the MCFZ. Directly east of the MCFZ gouge, is a silicified fault corridor which is moderately mineralized in the Homestake area. Gold mineralization also occurs within the metasediments at Homestake, where both disseminated and vein-hosted gold occurs within the upper Calc-Silicate and Middle Marble formations.Hangar Flats DepositMineralization in the Hangar Flats Deposit is entirely intrusive hosted and is localized in and along the flanks of the MCFZ. The highest grades of gold, silver, and antimony occur within sub-vertical, north-plunging, tabular to pipelike breccia bodies formed at the intersection of the main north-south structural features and shallowly northwest-dipping dilatant splay structure. These mineralized breccia zones range from 16 ft to over 330 ft in true thickness and can be traced several hundred feet down dip. Disseminated replacement style gold mineralization occurs throughout the MCFZ and eastern footwall in higher-grade tabular breccia zones. Disseminated gold mineralization also occurs as shallowly dipping tabular bodies along the northwest dipping splay structures, which pinch out to the east away from the main MCFZ. Alteration zonation is similar to that developed in the Yellow Pine deposit, but more tightly constrained to structures.West End DepositMineralization in the West End Deposit is structurally and stratigraphically controlled. Within the WEFZ, gold mineralization occurs within silicified breccia zones, sheeted quartz-adularia vein arrays and as replacement style mineralization situated where the northwest striking, northeast dipping calc-silicate and schistose units intersect the WEFZ. Alteration is dominated by sulfide replacement of iron-bearing mineral phases in favorable metasedimentary rocks and associated with quartz-potassium feldspar replacement and quartz-adularia-carbonate-sulfide veining. These mineralized zones occur as stacked ellipsoidal bodies plunging along the intersection of favorable lithologic units and faults zones and as tabular bodies extending along bedding. Mineralization also occurs as fracture filling within siliciclastic sequences and other less favorable lithologic units. True widths of these bodies range from 50 ft to over 330 ft. Drilling by Perpetua Resources has intersected gold mineralization associated with the WEFZ well below the historic pit bottom as deep as 1,300 ft below the original ground surface - where mineralization was exposed prior to mining. The hanging wall of the WEFZ tends to exhibit relatively more dilatant and dispersed structures relative to the footwall and, therefore, is more significantly mineralized. Open-space-fill quartz veins and silicified breccias are typical within higher-grade zones of mineralization. The degree of oxidation in the West End Deposit is a function of both depth and proximity to faults and fractures. Both pervasive and fracture hosted oxidation is common throughout the deposit to depths of approximately 300 ft below the pre-mining topographic surface. Discrete zones of pervasive oxidation occur below this depth in the vicinity of the WEFZ and subsidiary structures. Oxidation is interpreted to have resulted from both infiltrating precipitation and from deep-seated circulation of meteoric fluids through structural zones.
The Stibnite Gold Project mine plan consists of mining three primary mineral deposits and re-mining the Historical Tailings using conventional open-pit shovel and truck mining methods. The open-pit shovel and truck mining method was selected as it is a proven method previously used on this property. The method is best for lower-grade deposits where bulk methods, like shovel and truck mining, reduce the overall mining costs, and the mining of four separate deposits utilizes the flexibility of shovel and truck mining. The mining operation will deliver 8.05 million short tons (st) of oxide and sulfide mineralized ore to the crusher per year (nominally 22,050 st per day).Ore from the three open pits, Yellow Pine, Hangar Flats, and West End, will be sent to either the crusher located near the processing plant or one of several ore stockpiles located throughout the Project site. The Historical Tailings will be trucked to a re-pulping facility adjacent to the tailings deposit and hydraulically transferred to the process plant grinding circuit via a re-pulping facility.Most of the development rock from the three open pits will be sent to one of five destinations: the TSF embankment, the TSF Buttress, the Yellow Pine open pit backfill, the Hangar Flats open pit backfill, and the West End open pit backfill.Pit Design ParametersThe ultimate pit design for each pit was based on the selected pit shells and the pit design parameters:• Bench Height - 20 ft (Single bench ore mining); 40 ft (Double bench waste mining; final pit configuration);• Bench Face Angle - 63° (Bedrock); 45° (Alluvium);• Catch Bench Width - 20 ft;• Inter-ramp Angle 36° to 47°;• 150t Truck Ramp Width (2-Lane) - 102 ft (Including berm and ditch);• 45t Truck Ramp Width (2-Lane) - 50 ft (Including berm and ditch);• 150t Truck Running Surface - 81.1 ft (3.5 x truck operating width);• Safety Berm Height - 5 ft (½ truck tire height);• Safety Berm Width - 16.9 ft (width at base); 1.9 ft (berm top);• Road Ditch Width - 4 ft;• Maximum Ramp Gradient - 10% (150t haul trucks); 12% (45t articulated trucks);• Minimum Road Bend Radii - 64 ft;• Minimum Production Fleet Bench Width - 250 ft (benches less than 250 ft wide are mined with the development fleet).Yellow Pit Phase DesignIn addition to the nested pit shells produced in the Ultimate Pit Limit Analysis, a suite of directional pit shells was generated for the Yellow Pine deposit to identify potential for mining the main portion of Yellow Pine first and the northern Homestake area last. This phasing sequence allows for accelerated access to high-value ore deep in the central Yellow Pine deposit and provides for a short development rock haul from the Homestake area to the Yellow Pine pit backfill to reduce haulage cost.Hangar Plates Phase DesignThe Hangar Flats pit design consists of a single phase due to its small size and steep topography which requires a topdown mining approach. An internal phase within Hangar Flats would likely result in very narrow bench widths in the northwest highwall causing significantly reduced mining production rates.West End Pit Phase DesignFour pit phases were designed for the West End pit: (1) Middle Marble limestone mining, (2) Midnight area pit production, (3) South West End pit production, and (4) Main West End pit production. Mining limestone from the Middle Marble geologic unit located in the northeast portion of the West End open pit is required for the lime kiln to produce lime used in ore processing. The Midnight Area phase sequence is primarily driven by when access is available for backfilling this area using development rock produced in the Main West End phase. The South West End phase is accessible via the ROM-to-West End Haul Road and can be mined independent of the Main West End phase. The Main West End phase does not benefit significantly from additional phasing due to the homogeneous nature of the ore body.Historical Tailings Pit Phase DesignThe 2,687 kt of Historical Tailings will be excavated and hauled by truck to a nearby handling facility where it would be screened, re-pulped, and pumped to the grinding circuit. For mine planning purposes, the Historical Tailings resource is modeled with constant grade and value throughout the deposit. Therefore, phasing the Historical Tailings is not influenced by advancing access to higher value ore but instead by the need to accommodate construction of adjacent facilities and avoid costs associated with double handling of the material. The Historical Tailings are planned to be excavated and processed during the first 4 years of mill operation.EquipmentThe Project mine production fleet is typical for an open pit hard rock mine consisting of loading equipment (i.e., hydraulic shovels and wheel loaders), haul trucks, blast hole drills, and large dozers.
• Crushing Circuit - ROM material would be dumped directly into the primary crusher feed hopper or onto ROM stockpiles and the primary crusher discharge is delivered to the coarse ore stockpile. The coarse ore stockpile provides 12-hour live capacity. The crushing circuit design is based on a 24-hour per day, 365-day year operation at an average utilization of 75% yielding an instantaneous design throughput of 1,225 stph.• Grinding Circuit - The grinding circuit incorporates a single semi-autogenous (SAG) mill, single ball mill design with an average utilization of 90%, yielding an instantaneous design throughput of 1,021 stph. When Historical Tailings are processed during early years of the operation, the slurry from the tailings repulping plant would also flow into the cyclone underflow tub. Cyclone underflow flows by gravity to the ball mill. The cyclone overflow, at 35% solids with a target size of 80% passing (P80) 85 microns, is screened to remove tramp oversize and flows through a sampler and on to the antimony or gold rougher flotation circuit, depending on the antimony concentration of the material.• Sb Concentrate Regrind Mill: SMD-1100.• Lime Plant – Limestone Primary Crusher: Jaw Crusher, feed opening 42” x 28”; Limestone Secondary Crusher: HP 200 Standard Cone or equiv; Limestone Slurry Ball Mill 1 9.8’ x 15’ EGL overflow, SCIM on VFD.
The Project process plant has been designed to process both sulfide and oxide mineralized material from three deposits (Hangar Flats, Yellow Pine, and West End) as well as Historical Tailings from former milling operations. The design of the processing facility was developed based on the laboratory testing to treat 1,021 short tons per hour (stph) (excluding historical tailings) through crushing, grinding, flotation, concentrate oxidation, leaching by cyanidation, carbon handling and refining, oxide leaching, gold recovery, and tailings processing operations with a design availability of 90%.Run-of-mine (ROM) materials from the three pits and historical tailings have characteristics that require several process variations. Process variations are as follows:• Sulfide ROM with high antimony concentrations is crushed, ground, and treated in an antimony flotation circuit before sulfide flotation and pressure oxidation (POX) to release refractory gold for cyanide leaching and gold recovery;• Sulfide ROM with low antimony concentrations is sent directly from grinding to sulfide flotation, POX, leaching, and gold recovery;• Oxidized ROM is sent from crushing and grinding directly to a whole-ore cyanide leaching and gold recovery circuit, which is scheduled to be constructed when such ROM is anticipated in the mine plan;• Mixed sulfide and oxide (transition) ROM is handled as low-antimony sulfide ROM except that the flotation tailings are cyanide leached with the same circuit used for oxide material.Process DescriptionThe gold-bearing sulfide concentrate of pyrite and arsenopyrite is processed using pressure oxidation to break down the sulfide crystalline structure to liberate gold and silver to be leached and recovered to doré bars containing gold and silver. Small quantities of elemental mercury are collected in flasks to prevent its potential release into the environment. The design introduces Historical Tailings into the ball mill during the first 3 to 4 years of operation. Tailings from the operation are deposited in a geomembrane-lined tailings storage facility (TSF). The process operations are described as follows:• Flotation Circuit (Antimony and Gold) - The flotation circuit consists of up to two sequential flotation stages to produce two different concentrates; the first stage of the circuit was designed to produce an antimony concentrate when the antimony grade is high enough, or bypassed if not, and the second stage is designed to produce a gold-rich sulfide concentrate. The antimony flotation circuit includes a regind mill for size reduction. The antimony concentrate will be packaged and sold. The gold-rich sulfide concentrate will be stored in three agitated surge tanks.• Pressure Oxidation Circuit - Sulfide concentrate from the surge tanks is pumped to the autoclave feed tank. The autoclave is designed to provide 75 minutes of retention time at 220º Celsius (428º Fahrenheit) to oxidize the sulfides and liberate the precious metals. Autoclave discharge would be processed through flash vessels and gas discharge would be condensed and the remaining gas cleaned through a scrubber.• Oxygen Plant - An oxygen plant producing 670 stpd of gas at 95% oxygen and a gauge pressure of 40 bars is planned. The oxygen plant equipment is planned to be purchased from a vendor including installation supervision.• Lime Plant - Limestone quarried from the West End pit is hauled to an area south of the primary crusher pad. The material is crushed and screened to feed the limestone grinding mill. Ground limestone slurry and milk of lime are used to control acid in the autoclave, neutralize solutions and slurries coming out of the POX process, and control pH for leaching.• Oxidized Sulfide Processing - After pressure oxidation, slurry discharge from the flash vessels is neutralized and cooled prior to leaching. The slurry is leached in cyanide solution, followed by an eight-stage, pump-cell carbon-in-pulp (CIP) circuit for precious metal recovery from this high-grade stream. The sulfide CIP tailings are detoxified and discharged to the flotation tailings thickener. Alternatively, the sulfide leach tailings are combined with flotation tailings when the latter undergoes cyanide leaching, as described below.• Oxide CIP and Tailings Detoxification - A future oxide leach circuit is included in the design of the process plant to be running in Year 7 of mill operations. This circuit is designed to recover gold from non-refractory material in the flotation tailings when the mill is processing transition ore from the West End deposit. This circuit also directly processes oxide material from the West End deposit as a whole-ore leach process without undergoing flotation.• Carbon Handling - Loaded carbon from the CIP circuits is processed through a conventional carbon handling circuit, pumping eluant from the strip solution tank through heat exchangers to the bottom of the elution vessel at 45 psig and 293°F and a flow rate of 2 bed volumes per hour.• Gold Room - Precious metals are recovered from the strip solution by electrowinning, mercury retort, and a gold furnace that produces doré bars as a saleable product.• Tailings - Neutralized and thickened tailings are pumped from the process plant to the TSF in an HDPE-lined carbon steel pipe. Water produced by the settling of the tailings solids is reclaimed with barge-mounted pumps and returned to the process water storage tank.• Process Control Systems - The process plant design includes an integrated process control system.The two finished products from the Stibnite Gold Project ore processing facility will be: gold/silver bars, known as doré; and antimony-silver concentrate.
Water SystemsTwo types of water systems are required for the Project process plant: fresh water and process water. Fresh water for the Project would be supplied from multiple sources including wells, contact water ponds, and a raw water intake from the EFSFSR at the south tunnel portal.Groundwater wells located within the Meadow Creek valley alluvial deposits may contain elevated concentrations of metals and are considered to be the equivalent of contact water. Contact water includes seepage from storage piles and runoff from mine-impacted areas. Contact water from various sources would be pumped to the freshwater tank, which also serves as the firewater tank. Fresh water in the tank would be distributed to and used for:• the freshwater distribution system;• process water makeup;• the firewater pipeline loop;• the gland seal water tank and pumped by horizontal centrifugal pumps to be used as seal water for mechanical equipment;• the mine water trucks to be used in road dust control;• the process uses points (e.g., crusher dust suppression, reagent mixing, etc.).Process water would be reclaimed from several locations and returned to the process water tank. Overflow from the tailings thickener, water reclaimed from the TSF, contact and stormwater ponds would also be pumped to the process water tank.Water ManagementPerpetua Resources will develop a water management system that protects or improves water quality in Project-area streams and provides water for ore processing, fire protection, exploration activities, surface mining (dust control), and potable water needs.The key water management consideration for the Project site is the large amount of snowmelt runoff during the months of April through June, making spring melt the critical time for water management, storage, and treatment. In general, surface water that comes in contact with materials that have the potential to introduce mining- and process-related contaminants (contact water) is kept separate from surface water that originates from undisturbed, uncontaminated ground (non-contact water). This is accomplished by diverting clean water around mine facilities and collecting and reusing, evaporating, or treating and discharging contact water.Meteoric and tailings consolidation water will be reclaimed from the TSF and would supply the majority of the water needed for ore processing. Additional water needs would be supplied from: pit dewatering, reuse of stored contact water, groundwater wells, and a surface intake near the upstream portal of the EFSFSR diversion tunnel.Active dewatering will be required at the Yellow Pine and Hangar Flats pits, generally from alluvium and fractured bedrock wells, with total pumping ranging from zero to approximately 2,100 gpm over the life of mine. Excess dewatering water not used for ore processing would be treated, if required, and discharged to a surface outfall.Contact water from the pits, stockpiles, TSF buttress, truck shop, ore processing facilities, and legacy materials exposed during construction would be collected in lined ponds or in-pit sumps for later use in ore processing, dust control, or treatment for discharge. Water management features would be phased in and out as mining progresses and the amount of surface area generating contact water increases as pits, stockpiles, and DRSFs expand and are removed as backfilling and reclamation is completed. Aggregate contact water pond storage varies according to mine phase and is roughly 300 to 400 ac-ft over the mine life (excluding storage in pits).
Success!