Centrifugal Filtration Technology for Limestone Mine’s Substation

This powerhouse mine officially initiated its limestone mining and processing operations, within the Northern Cape province of South Africa in 1975. Today, the mine is one of the largest mining operations producing high-grade Calcitic Limestone.

The extraction and production of limestone starts its process at the open cast mine. Benches are created by means of blasting, which results in the fragmented material being released from the ore body. The fragmented material is crushed into smaller pieces and undergoes various screening processes, after which it is burned in the kilns.

During this process, an exceptionally large amount of dust is released, exposing sensitive electrical equipment – located in the onsite substations – to some of the dustiest conditions. Since the substations provide power to the plant machinery and processes on the mine, dust ingress may cause catastrophic failures.

When dust enters electrical equipment, it forms calcified bridges between the electrical circuits, creating the potential of a “spark-over”. Spark over renders sensitive electrical equipment (such as switches) irreparable, leading to costly downtime and the overall disruption of operations. The mine, therefore, required a solution to decrease the dust load in the substations.

The CFT pre-filter system offers
a cost-effective solution to this problem.

FloSolve proudly installed a room ventilation solution, which generates pressure through a 2-stage filtration process. The act of over-pressurising a room is common practice within electrical substation applications where a clean environment is required for optimal performance. By pressurising the room, any dust which may have been drawn into the substation’s room by means of natural aspiration, is eliminated due to its inability to enter the room through unsealed areas such as door and window seals.

It is, however, important to ensure that the air utilised towards pressurising the room is clean. The 2-stage filtration system is designed to filter the air before it is used in the process of pressuring the room. Filtration is done by means of Centrifugal Filtration Technology (CFT) and takes the form of the CFT pre-filtration apparatus and a high-efficiency pocket air filter.

The air pocket filter is designed to remove any fine particles within the 01 – 10 μm range. Therefore, since one filter can run a cost of around R3 000, it is not economical to “waste” this filtering ability on larger particles.

This is where the CFT pre-filter shines.

With no moving parts and its ability to remove 92% of particles greater than 5 μm, the CFT pre-filter extends the overall filter life of the pocket air filter significantly. Additionally, the CFT pre-filter allows the pocket filter to remove any small particles, as was intended.

By utilizing both the CFT pre-filter and the pocket filter, clean air is provided in adequate quantities to fully pressurize the substation’s room and subsequently, reduce the dust load.

This in turn, results in less downtime due to spark-over, and improved electrical system reliability.

The benefits of the CFT pre-filter system:

• Extended Filter Life
• Reduced Downtime
• Reduced Maintenance / Operational Costs
• No Moving Parts