Introduction
Ukrainian mining and extraction industry operates under conditions of high dynamic loads, abrasive wear and continuous working cycle. Enterprises in this sector face critical need of ensuring high equipment availability. Any unplanned downtime of mining or processing complex leads to significant financial losses. Maintenance (MRO) in this sector requires strict adherence to schedules and use of certified components complying with ISO and DSTU standards.
The hydraulic circuits of heavy mining equipment are based on high-performance hydraulic distributors. Among them, the industrial standard is set by devices of the VICKERS C5G-815 series. They control the flow of working fluid under high pressure in the drives of crushers, mills, and conveyor lines. The application of such units requires a deep understanding of their construction, operating modes, and specifics of technical maintenance according to European standards EN.
Critical components of hydraulic systems in the mining industry
The hydraulic system of the mining and processing complex is a complex energy system. In it, the hydraulic distributor VICKERS C5G-815 serves as the main actuating element, which directs the oil flow under pressure to the actuating cylinders and hydraulic motors. This component is rated for a working pressure up to 320 bar and oil flow rates that ensure a quick response of heavy mechanisms.
In addition to VICKERS C5G-815, the stability of the hydraulic system is ensured by other critically important components:
- Asymmetric axial piston pumps (for example, series Rexroth A4VSO) for pumping working pressure.
- Two-port and three-port cartridge pressure and flow control valves (Sun Hydraulics).
- Filtering elements for fine cleaning with β10(c) ≥ 200 according to ISO 16889.
- Plate and shell-and-tube heat exchangers for maintaining oil temperature within the range of +45...+55 °C.
- Electromagnetic feedback sensors and pressure relays with IP67 protection class.
Typical layout scheme of equipment on a concentrator plant
The technological process of ore extraction and primary processing covers several consecutive stages. On each of them, hydraulics plays a key role:
- Crushing Department: Primary and secondary crushing of iron ore or granite. Hydraulic drives adjust the width of the discharge opening of cone crushers and protect them from the entry of non-crushable objects.
- Mill section (semi-autogenous mills and ball mills): Lubrication of sliding bearings under high pressure and drive mechanisms for lifting mechanisms of the lining.
- Classification and flotation section: Control of large diameter shut-off valves and slurry pumps using positioners.
- Contamination of the working fluid with solid particles (dust, scale, wear products), leading to sticking of the spool in the body.
- Cavitation erosion of internal surfaces due to pressure drop below the saturation vapor level.
- Thermal degradation of sealing materials (viton and nitrile) when the operating oil temperature exceeds +70 °C.
- Electrical coil wear due to vibrational loads (oscillation frequency up to 50 Hz).
- Replacement of filter elements of the hydraulic station every 500 hours of operation.
- Checking of connection tightness and bolt torque according to EN ISO 4014.
- Control of olive oil class (not worse than 16/14/11 according to ISO 4406).
- Installation of vibration sensors on the housings of hydraulic distributors and pump units.
- Online monitoring of temperature and humidity in the hydraulic tank.
- Measurement of valve response time using electrical feedback signals.
- Disassembly of the mounted unit after releasing the residual pressure in the main lines to 0 bar.
- Cleaning the mounting plate and checking the seating surface flatness according to standard ISO 4401.
- Installation of new VICKERS C5G-815 distributor with compliance to the tightening torque of the mounting screws of strength class 12.9.
- Circulating the system with working fluid and calibrating pressure sensors.
- Strategic stock (Critical Spares): Minimum 1 fully assembled and tested hydraulic distributor at the company's central warehouse.
- Витратні матеріали: Комплекти ущільнень (FKM/Viton), з'єднувальні кільця O-ring за стандартом ISO 3601, фільтроелементи в кількості триразової потреби на місяць.
- Logistics: Reliable supply channels from European warehouses through certified distributors, ensuring delivery to Ukraine within 48–72 hours.
- ISO 4406: Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles.
- ISO 16889: Hydraulic fluid power — Filters — Evaluation of filtration performance for filter elements.
- ISO 55001: Asset management — Management systems — Requirements.
- EN ISO 4014: Hexagon head bolts — Product grades A and B.
- DSTU GOST 17411: Hydraulic systems. General technical requirements.
In this architecture, the hydraulic distributor VICKERS C5G-815 is usually installed in close proximity to the power hydraulic cylinders of crushers or gap adjustment drives. This minimizes hydraulic pressure losses in the main lines and ensures the system's response speed during overloads.
Failure Modes and Impact on Plant Downtime
Operating conditions in mines and quarries cause specific types of hydraulic equipment failures. The main causes of failure of VICKERS C5G-815 and related components are:
Financial losses from emergency stoppages at Ukrainian mining and processing plants are extremely high due to the continuous nature of production. The cost of downtime for the coarse crushing line or main conveyor is shown in the table below:
| Type of equipment | Line productivity | Average losses per hour of downtime (€) |
|---|---|---|
| Coarse Cone Crusher | 800 t/year | 14 500 – 22 000 |
| Half-automatic milling (MNS) | 450 t/year | 18 000 – 28 500 |
| Main ore conveying conveyor | 1200 t/year | 9 500 – 15 000 |
Maintenance Strategies: Preventive versus Predictive
Transition from reactive maintenance to predictive strategies (Condition Monitoring) is mandatory for modern enterprises according to the recommendations ISO 55001 (Asset Management).
«Regular laboratory analysis of oil according to standards ISO 4406 allows detecting wear of spool pairs VICKERS C5G-815 up to 200–300 hours before complete mechanism seizing».
Preventive Maintenance (PM):
Predictive maintenance (PdM):
Case Study Analysis: Restoration of the Crushing Unit's Operational Capability
An incident occurred at one of the mining and processing plants in the Krivoy Rog basin, where a conical crusher stopped due to an emergency drop in pressure in the control hydraulic system of the discharge gap. Initial diagnostics showed internal oil bypassing in the VICKERS C5G-815 hydraulic distributor due to wear of the spool working edge.
Emergency repair by the service team took 6 hours instead of the standard 36 due to the availability of a certified repair kit and a spare unit on stock. The sequence of works included:
Thanks to the fast node replacement, the company avoided losses of over 90 000 euros.
Spare Parts Management
Effective MRO inventory management for the mining industry requires balancing the risk of long downtimes and the freezing of working capital. For critical components, such as VICKERS C5G-815, the Min-Max Inventory strategy is applied.
For selection of original components and checking availability of required positions, we recommend using UNITEC-D E-Catalog, where a wide range of industrial hydraulics with CE documentation is presented.
Conclusion
Reliable operation of hydraulic equipment in the mining industry is a guarantee of continuous production processes. The use of quality components, such as the hydraulic distributor VICKERS C5G-815, in combination with compliance with ISO and EN regulations, minimizes the risks of emergency shutdowns. Investments in predictive diagnostics and proper management of inventory reserves are justified due to the saving of millions of company budgets.
