| Company | Venture Gold Inc. |
| Date | January 2023 |
| Region | Clear Creek County, Colorado |
| Commodities | Gold, Silver |
Executive Summary
Venture Gold Inc. has established a fully permitted mill site at Hukill Gulch in Clear Creek County, Colorado. This facility is designed to process sulfide ores containing gold and silver. Currently, the mill operates at a capacity of 60 tons per day on a stand-by basis, with plans to upgrade to 300 tons per day to support the Old Town Mine Project.
The Hukill Gulch Mill utilizes a processing circuit that includes crushing, ball milling, gravity concentration via centrifuge, and flotation. The site holds a Limited Impact 110(d) permit allowing 70,000 tons per year throughput. Venture Gold intends to process lower-grade mine dumps initially before transitioning to high-grade underground ore from the Old Town Mine Project.
Venture Gold is also evaluating the possibility of building a 1000 ton per day mill on the prairie east of the mountains to fully develop the district. The current mill facilities are maintained on a stand-by basis, with pilot-scale operations reported to have proven successful since 2011.
Processing Profile
Reports
- reports/2023_Venture_Gold_Old_Town_Mine
Website: https://www.ctvnews.ca/business/article/3-billion-canadian-merger-is-fast-tracking-gold-production-in-guyana/?shem=dsdf%2Csharefoc%2Cagadiscoversdl%2C%2Csh%2Fx%2Fdiscover%2Fm1%2F4
Report Date: January 2023
Region: Clear Creek County, Colorado
Project Status:
Commodity: Gold, Silver
Throughput:
Mine Life:
Mine Type:
Ore type:
Technical report and processing history
The following archived source profiles have been consolidated here to preserve the project’s processing history and study context.
Technical Analysis of the Old Town Mine: A Hub for Denver Mineral Processing Excellence
Overview
The Old Town Mine Development Project, spearheaded by Venture Gold Inc. (and its affiliate Venture Mill Company LLC), represents a significant milestone in the revitalization of historical mining districts in the United States. Located approximately 30 miles west of Denver, Colorado—specifically within the Upper Russell Gulch of Gilpin County—the project is positioned in one of the most storied mineral provinces in North America. This district, often referred to as the “Richest Square Mile on Earth,” is estimated by some geological surveys to contain a staggering potential of up to 100 million ounces of gold yet to be fully developed and extracted. The Old Town Mine itself is a cornerstone of this district, sitting roughly four miles north of Idaho Springs and two miles south-southwest of Central City.
The project’s significance is twofold: it combines the extraction of high-grade underground resources with the immediate processing of extensive surface stockpiles. Historical operations by the former Old Town Mining, Milling, and Transportation Company left behind approximately 5,000,000 tons of low-grade gold ore in surface mine dumps. These stockpiles, which average approximately 0.12 oz/ton of gold, provide a ready-made “low-hanging fruit” for the project’s initial processing phases while richer underground veins are being developed for long-term production. The strategic location near Denver allows for seamless access to professional metallurgical services, such as those provided by the Denver Analytical Laboratory, ensuring that the project benefits from high-level technical oversight and consistent assaying of sulfide ores. By integrating modern modular processing technology with historical resource bases, the Denver-area project serves as a model for brownfield redevelopment in the 21st century.
Key Process Stages
The mineral processing circuit at the Old Town Mine and the associated Hukill Gulch Mill (Hukill Mill) is designed to handle gold and silver bearing sulfide ores through a combination of traditional gravity concentration and advanced flotation techniques. The circuit is characterized by its modularity and scalability, transitioning from pilot-scale 60 tons per day (tpd) to a planned 400 tpd capacity. The primary stages include:
- Primary Crushing: Run-of-Mine (ROM) ore is reduced to a maximum size of approximately 1 inch using a heavy-duty primary crusher. This stage is critical for ensuring consistent feed size for downstream milling.
- Screening and Classification: Crushed ore is passed through a 3/16-inch mesh vibrating screen. Oversize material is directed to the ball mill, while undersize material proceeds to specialized “Denver Sub-A” unit cells for immediate sulfide removal.
- Gravity Concentration: Utilizing Denver Mineral Jigs (typically in 12″ x 18″ or 16″ x 24″ configurations), the circuit recovers coarse-grained gold and heavy minerals early in the process. This prevents “over-grinding” of the gold, which can lead to recovery losses.
- Milling and Grinding: A Marcy-style compensating grate ball mill or equivalent grinding unit reduces the ore to a target particle size of 80% passing 200 mesh (75 microns). This liberation step is essential for exposing the gold particles within the sulfide matrix.
- Flotation Recovery: The core of the sulfide recovery utilizes Denver Sub-A flotation machines. This stage typically consists of a bank of rougher cells and cleaner cells (e.g., a 6-cell configuration) to produce high-grade silver, copper, lead, and zinc concentrates.
- Thickening and Filtration: The final concentrate is sent to a thickener tank and then through a filter press (such as a Diemme plate and frame press) to reduce moisture content to approximately 8-10%, preparing it for transport to smelters.
- Tailings Management: Final tailings are thickened to recover process water and then stored in approved tailings management facilities, adhering to the strict environmental standards of the Clear Creek watershed.
Critical Data
The following table summarizes the key technical parameters and performance metrics for the Denver-based Old Town Mine Development Project based on technical reports and pilot-scale data.
| Parameter | Value | Unit |
|---|---|---|
| Stockpile Resource | 5,000,000 | Tons |
| Average Stockpile Grade | 0.12 | oz/ton Au |
| Initial Design Throughput | 300 | tpd |
| Expansion Design Capacity | 400 | tpd |
| Annual Processing Ceiling | 70,000 | tpy |
| Project Duration (LOM) | 25 | Years |
| Target Grind Size (P80) | 75 | Microns (µm) |
| Gravimetric Gold Recovery | 30.0 | % |
| Gravimetric Silver Recovery | 10.0 | % |
| Estimated Process Availability | 91.3 | % |
| Tailings Disposal Cost | 4.00 | $/ton |
| Potential District Resource | 100,000,000 | oz Au |
Technical Details and Sustainability
A distinctive feature of the Denver project is its commitment to modular processing. The implementation of modular gold plants—potentially expanding to dual 2,000 tpd units for large-scale operations—allows for a significant reduction in initial capital expenditure and onsite construction time. These modular units are pre-fabricated and tested, ensuring that the recovery circuits (gravity and flotation) are fully optimized before deployment. The use of Denver Sub-A flotation technology is particularly noteworthy; these cells are renowned for their ability to handle varied feed grades and provide high selectivity, which is vital when processing complex sulfide ores from multiple historical mine dumps.
Sustainability and environmental stewardship are at the heart of the project’s technical planning. The Old Town Mine is situated within the Clear Creek/Central City Superfund Site, an area-wide National Priorities List (NPL) site. This location necessitates a highly sophisticated approach to water management and tailings disposal. The project utilizes the Argo Tunnel (also known as the Newhouse Tunnel) for historical drainage management, and all new operations must comply with the Colorado Division of Reclamation, Mining and Safety (DRMS) and the US EPA. The processing circuit is designed to be a “closed-loop” for water, with thickeners recovering a high percentage of process water to minimize the draw on local resources. Furthermore, the development plan emphasizes the “step-by-step” redevelopment of the district, which allows for environmental remediation of historical mine dumps while generating economic value. This “cleanup through mining” approach is a sustainable alternative to traditional remediation, as it removes potentially acid-generating sulfides from the surface and places them in modern, lined tailings facilities.
Looking to the future, the project aims to transition from the current stand-by/pilot phase into full-scale 400 tpd production. The scalability provided by the modular design ensures that as the underground resource is further defined through drilling, the processing capacity can be increased with minimal disruption. The integration of modern automation—such as PLC-controlled water addition and belt scales—enhances metallurgical accounting and ensures that the recovery of gold and silver remains consistent even as ore characteristics change. With a projected 25-year life of mine, the Old Town Mine project near Denver stands as a testament to the enduring potential of historical mining districts when approached with modern technical innovation and environmental responsibility.
Source: Denver
Source: NI 43-101 Technical Report
This article provides an overview of mineral processing developments based on publicly available technical reports and industry analysis.
