Keeping mines and infrastructure dry

Keeping mines and infrastructure dry

Ingress of groundwater is one of the leading causes of production loss and damage to infrastructure. Henk Pretorius of ISO shares some cutting-edge innovations and insights with Dr Nicolaas C Steenkamp.

Ingress of groundwater into underground operations or large-scale excavations is one of the leading causes of production losses or damage to infrastructure. ISO (Industrial Synthetic Oils) was established by Henk Pretorius in 1992 manufacturing synthetic lubricants and to service the niche market of water-sealing and related services.

Based in Parys, Free State, previously Bothaville, South Africa, the company is centrally located to service the whole of Southern Africa and international markets. The main services provided by ISO are: manufacture, supply and application services for water, methane and strata control.

The service provided is a highly technical area of expertise, ranging from developing tailor-made sealing solutions to void-filling and water management rolled into one. Over the years ISO has developed a number of unique polymers for application in various challenging areas. Pretorius goes on to explain, “Traditionally water influxes into shafts meant loss of production for weeks or in some known cases up to years of production were lost.”

The development of materials and equipment that took the guess work out of water sealing has seen these downtimes turned into production times. Developing injection materials where the gel-time (the phase where the liquid turns into a solid) can be accurately controlled was the first step into time saving. Applying known scientific hydraulic models plus integrated research brought about revolutionary changes. From connecting a huge pump with an enormous mixing barrel whirling out tons of cement slurry with an unknown allusion or notion of the duration it became possible to calculate and estimate the quantities and duration of a typical grout operation.

Injection materials can now be matched to the application. The target injected area can now be predetermined. The target volume of grout can now be scheduled. The duration of the operation can now be timetabled. Surprise ‘leaks’ during injections can be effectively sealed without stopping the grout operation.

The main project-works ISO undertakes is water and methane sealing in hard rock environments. This requires sealing groundwater inflow at specific features such as joints or fissures. “It is quite a task to stem the flow of this water, especially at depth and with working height restrictions,” remarks Pretorius. Uncontrolled water influxes need specific skills for containing the same. Our highly experienced grout technicians have been tasked on a number of occasions with uncontrolled volumes of up to 300 000ℓ of water and hydrostatic pressures up to 65bar, water temperatures up to 65°C in mines close to inactive volcanos.

Innovation at ISO is not limited to grouting and water-sealants, but also incorporates task specific development of instruments, tools and equipment. Pretorius notes that, “Research and development remain at the forefront in order to remain the water-sealing contractor of choice.” During a recent decline remedial project, a vehicle had to be developed that was able to operate in the constrained space of the decline and move rapidly enough to complete the work in the limited working window made available. Personnel safety was of primary concern and drilling was done remotely.

A number of different attachments were developed, this allowed drilling of holes in the lining, before an interchangeable attachment was used to pump void fill material and water-sealing resin. An additional attachment could be attached to clean the floor of the decline prior to operational vehicles entering the decline, making it safe for travel. The same vehicle doubled up as a transporter to move the injection materials down the decline. The vehicle was able to pass the stringent engineering requirements of the mine, a feat in itself.

Current developments that will earn novel status in the sub surface injection world is a remote operated self-intelligent pump system which is in the final stages of development.

ISO has tackled some of the most challenging jobs in the mining and construction spheres. The company was instrumental in developing a pre-grouting resin that could be pumped into unconsolidated sediments around the collar of a planned shaft. The resin served a dual purpose, stabilising the sediments and preventing groundwater ingress, required for safe excavation of the shaft during the pre-sink phase.

“The company has also recently been involved in sinking of two shafts in the Kalahari Manganese Fields, through the iconic thick red sands,” adds Pretorius. In parallel the decline remedial work was also completed, this entailed filling the self-mining voids that had developed behind the decline lining due to groundwater ingress in the unconsolidated gravels, calcrete and highly weathered tillite.

Pretorius goes on to describe, “The main challenge of working in an unconsolidated material, is that groundwater flow is dynamic. As soon as an ingress level is sealed, the water migrates to a different position. This required the void filling and water sealing to be done in a highly planned manner. Void filling and water sealing was done from the bottom upward, driving the water to positions where stainless steel telescopic taps were installed. In vertical shafts the modus operandi is the opposite where sealing is done top down. The mine required the water from the declines to still be available for underground workings. This required a down-decline water management plan.”

One the other extreme end of the spectrum ISO has also been involved in developing water-sealing solutions for a shaft being sunk in permafrost. Pretorius describes these experiences as ‘confrontational’. In the CIS countries the mining industry is rapidly expanding. These expansions have unique challenges not seen in South Africa. Permafrost, thick clay and sand overlays and totally water-logged sands to a greater magnitude are in these mines.

Looking forward, Pretorius expresses the opinion that, “In the near future, most if not all operations will need to expand into more challenging underground environments to develop the remaining portions of their orebodies. This goes hand-in-hand with requiring more advanced water-methane and strata control solutions.”

Pretorius concludes, “We would like to thank our customers for the trust and opportunities that is offered to ISO in support of improving the world of the miner.”

<images>

Yes, 1

 

Pin It
Home News News Archive Keeping mines and infrastructure dry

Connect with us

Talk to us

Available Monday - Friday, 8 AM - 4 PM
Call usemail us