80TPH Ball Mill Grinding Circuit for Gold Ore Processing in Peru

Project Background

Minera Inca Gold SAC, a Peruvian artisanal-to-medium-scale gold mining company operating in the Cajamarca region, decided to invest in a modern ball mill grinding circuit to replace an ageing and inefficient stamp mill system. The company's technical manager, Mr. Juan Pablo Quispe, began evaluating ball mill suppliers in early 2023. He found Xianglong Machinery through a Google search for "ball mill for gold ore manufacturer" and also connected with XLM on LinkedIn, where he found technical articles on ball mill sizing for gold ore applications. He sent a connection request and direct message via LinkedIn and was promptly contacted by XLM's Latin America sales engineer, Mr. Kevin Liu.

Channel Communication and Needs Assessment

Mr. Liu arranged a WhatsApp video consultation with Mr. Quispe and XLM's grinding specialist, Mr. Henry Wu. The gold ore at the Cajamarca site was a gold-silver bearing quartz-pyrite ore with a Bond Work Index of approximately 13-15 kWh/t, a feed size of minus 25 mm from the secondary jaw crusher, and a target grind size of P80=74 microns for optimal gold and silver recovery in the downstream CIL circuit. The required throughput was 80 tonnes per hour.

Technical Solution and Engineering Alignment

Henry Wu designed a single-stage ball mill grinding circuit using a MQG-3.2x6.0 Ball Mill in closed circuit with a hydrocyclone classifier. The Ball Mill was lined with a rubber liner system to minimise wear in the moderately abrasive quartz-pyrite ore, and was paired with a ZSW-490x110 Vibrating Feeder for controlled feed rate management. Henry provided detailed power consumption calculations demonstrating that the new mill would consume 14% less energy per tonne of ore processed compared to the existing stamp mill system.

Technical discussions were conducted over five weeks via WhatsApp and email. Henry's team provided detailed installation drawings, foundation designs for the Cajamarca site's seismic zone classification (Peruvian NTE E.030 seismic code, 8-degree seismic fortification with base isolation considerations), and a comprehensive spare-parts package for 12 months of operation. High-altitude adaptations were engineered for the 2,800-3,500m elevation range: the MQG-3.2×6.0 Ball Mill drive motor was uprated from 710KW to 850KW to compensate for altitude derating (approximately 10% power loss at 3,000m), girth gear lubrication was specified with high-altitude gear oil formulations, and the mill's discharge trunnion was designed with enhanced ventilation to prevent vapor lock in thin air. Rubber liner compounds were formulated for UV resistance given the intense solar radiation at altitude. Spanish-language operation and maintenance manuals were provided. The contract was signed in March 2023, with a delivery period of 85 days.

Delivery, Installation, and Commissioning

Equipment was shipped from Qingdao to Callao port and transported by road to the Cajamarca site. XLM dispatched grinding engineer Mr. Henry Wu and mechanical specialist Mr. Chris Fang to Peru for a 20-day commissioning engagement. The Ball Mill achieved 82TPH at P80=71 microns during the acceptance test, exceeding both throughput and fineness targets.

Results and Client Feedback

Within three months of commissioning, Minera Inca Gold reported that the improved grind fineness had increased gold recovery in the CIL circuit by 5.8 percentage points -- from 88.2% to 94.0% -- a highly significant improvement at the prevailing gold price. The additional annual revenue from the improved recovery was estimated at approximately USD 2.1 million. Mr. Juan Pablo Quispe stated: "XLM's Ball Mill has transformed our processing plant. The improvement in gold recovery has exceeded our most optimistic projections, and the energy savings have reduced our operating costs significantly. We are planning to expand our Cajamarca operation and will source all additional grinding equipment from Xianglong Machinery."