I. Core Application Scenarios

1. Fine Grinding of Metal Ores (Mainstream Scenario)

• Ferrous Metal Ores (Iron Ore, Manganese Ore): Used for fine grinding of hematite, magnetite and manganese ore. After grinding, it is suitable for magnetic separation or flotation processes, improving the recovery rate of useful minerals such as iron and manganese, especially suitable for the in-depth utilization of low-grade iron ore;

• Non-ferrous Metal Ores (Copper, Lead, Zinc Ore): For chalcopyrite, sphalerite, galena, etc., fine grinding fully exposes useful minerals, facilitating the adhesion of flotation reagents, improving concentrate grade and reducing mineral processing loss;

• Precious Metal Ores (Gold, Silver Ore): Used for fine grinding of gold and silver ores, especially suitable for heap leaching and cyanide leaching processes. Grinding the ore to a uniform fineness accelerates the leaching speed and improves the extraction efficiency of gold and silver.

2. New Construction and Commissioning of Small and Medium-sized Metal Mines

3. Technical Renovation and Capacity Expansion of Old Mines

4. Low-grade Ore and Tailings Reutilization

5. Temporary/Mobile Grinding Operations

II. Suitable Models and Core Advantages

1. Main Suitable Models

• Used Grid-type Ball Mill (Φ1.83×7m-Φ3.2×13m): Suitable for small and medium-sized metal mines with a daily processing capacity of 300-1500 tons, mainly used for rough grinding and fine grinding of conventional metal ores such as iron ore and copper ore, with uniform product particle size and high processing efficiency;

• Used Overflow-type Ball Mill: Finer grinding fineness (up to below 0.074mm), suitable for fine grinding of precious metal ores (gold ore, silver ore) and rare metal ores, suitable for leaching processes, improving metal extraction efficiency;

• Used Energy-saving Ball Mill: Energy consumption is 15%-25% lower than that of ordinary ball mills, suitable for large-scale continuous production of metal mines, especially for large-scale processing of low-grade ores, reducing operating costs.

2. Core Advantages (From the Perspective of Metal Mines)

• Low Investment Cost: The price of used equipment is only 30%-60% of that of new equipment, which greatly reduces initial equipment investment, eases the capital pressure of mines, shortens the payback period by more than 30%, and is suitable for small and medium-sized mines with limited funds;

• Fast Commissioning: Spot supply, no need for customized production, short installation and commissioning cycle (10-20 days), and production can be achieved in as fast as 15 days, quickly connecting the crushing and mineral processing processes to avoid production disconnection;

• Strong Adaptability: The specification and filling rate of grinding media (steel balls) can be flexibly adjusted according to the type of metal ore, ore hardness and target grinding fineness, adapting to different production needs and strong versatility;

• Controllable Risk: The core components (cylinder, liner, motor) of used ball mills are durable and can operate stably for a long time after maintenance. They have stable residual value and can be leased or resold according to production needs in the later stage, reducing the risk of equipment idleness;

• Low Maintenance Cost: Spare parts are highly versatile, the purchase cost of wearing parts such as liners and steel balls is 40% lower than that of new equipment, the maintenance technology is mature, no professional customized maintenance services are needed, and ordinary maintenance personnel can complete daily maintenance.

III. Selection and Operation Points (Key to Avoid Pitfalls)

1. Core Selection Indicators

• Cylinder Condition: Check the thickness of the cylinder (remaining thickness ≥70% of the original thickness), no cracks, deformation, severe wear, the integrity rate of the liner ≥80%, to avoid ore leakage and dust leakage during grinding;

• Core Components: Check the wear of grinding media (steel balls) and the operation status of transmission devices (gears, motors), ensure good insulation performance of the motor, stable transmission without abnormal noise, and no severe wear of bearings;

• Process Adaptation: Select the model according to the ore type and target grinding fineness. Prioritize grid-type ball mills for rough grinding, and overflow-type ball mills for fine grinding and leaching processes, matching the daily processing capacity demand;

• Equipment Source: Prioritize formal used equipment dealers and equipment eliminated by mine technical renovation, and ask for equipment factory certificate, maintenance records and operation ledgers to avoid refurbished machines and major repaired machines, ensuring that the actual working condition of the equipment is consistent with the marked one.

2. Operation and Risk Control

• Preliminary Maintenance: After purchase, conduct a comprehensive inspection of the cylinder, liner, transmission system and sealing device, replace aging liners and seals, supplement or replace grinding media, and ensure the tightness and grinding efficiency of the equipment;

• Environmental Adaptation: A large amount of dust will be generated during the grinding process, which needs to be equipped with used dust removal equipment to ensure that the dust emission meets environmental protection standards, avoid environmental risks, and protect the health of operators;

• Reserve Budget: Reserve budget for wearing parts (liners, steel balls) and daily maintenance. The annual maintenance cost of used equipment is about 15%-20% of the purchase price, avoiding production impact due to lack of spare parts;

• Operation Specifications: Equip professional operators, strictly control the feed particle size, grinding time and medium filling rate, avoid idling and overload operation of the cylinder, extend the service life of the equipment, and ensure that the grinding fineness meets the standard.

IV. Application Cases (Reference)

• Small and Medium-sized Iron Mine: Purchased a used grid-type ball mill (Φ2.2×7.5m) equipped with a classifier, with a total investment of about 900,000 yuan, used for fine grinding of magnetite, processing 600 tons of crushed ore per day, the qualification rate of grinding fineness is 98%, the magnetic separation recovery rate is increased by 12%, and the investment is recovered in 7 months;

• Copper Mine Technical Renovation: The old copper mine added a used overflow-type ball mill (Φ2.4×10m) for fine grinding of chalcopyrite, completed installation and commissioning in 12 days, increased grinding capacity by 45%, increased concentrate grade by 8%, and saved 55% of the technical renovation investment compared with new equipment;

• Remote Gold Mine: Used a used mobile ball mill for pretreatment before gold ore leaching, flexibly transferred to 2 working faces, reduced ore haulage costs, obtained an additional annual income of 180,000 yuan by leasing after the project was completed, and the residual value of the equipment remained above 60% of the purchase price.

V. Summary