March 2010

Andru Mining passes on the value in South Africa's buoyant opencast sector

Mined on a daily two shift cycle, the deposit at Uitkyk, which has an anticipated life of mine to 2017, currently entails two box cuts, each with an average length of 900m and depth of 40m, with bench heights established at 15m. Average haulage distances for coal are around 1,3km and for rollover pre-strip between 500 and 600m.

Drilling and blasting, extraction and haulage, plus ongoing site remediation are the daily tasks performed by Gauteng based turnkey contractor, Andru Mining, as the company continues to drive down the cost per tonne across eight leading mines in South Africa's coal and chrome sectors. And to meet these production demands, Andru deploys a comprehensive range of some 250 items of capital equipment, each assigned with a designated role to make sure that the client's tonnage targets are achieved.

Four of these operations are in coal, with Andru on site at Shanduka Coal's Uitkyk and Townlands mines, in addition to Exxaro's Inyanda Colliery, and Umtombo Resources' Brummersheim colliery, a greenfields development which produced its first saleable product within a month of coming on stream.

At Shanduka Coal's Uitkyk pit in Middelburg, Andru first began mining on Shanduka's neighbouring Townlands pit in 2003 (referred to as "Block A", which as with adjoining "Block C" has now been fully rehabilitated). Currently, the two sites together provide a monthly output of around 330 000 tonnes per month (either export quality from Seam 1 or local supply for coal-fired power stations from Seam 2). This translates to around 950 000 banked cubic metres for both mines. Of this figure, Uitkyk ("Block B") yields the lion's share at around 220 000 tonnes of coal per month at a typical strip ratio of 3:2 (with a need to move around 700 000 banked cubes of overburden.)

"Block D at Townlands is now nearing its final productive life and the last three cuts are expected to be mined out by the end of May 2010," explains Rob Elphinstone, Andru Mining's managing director.

Mined on a daily two shift cycle, the deposit at Uitkyk, which has an anticipated life of mine to 2017, currently entails two box cuts, each with an average length of 900m and depth of 40m, with bench heights established at 15m. Average haulage distances for coal are around 1,3km and for rollover pre-strip between 500 and 600m.

Forming the backbone of its mining efficiencies, Andru's overall equipment capability at Uiykyk (which means "Lookout" in Afrikaans) is reinforced by its Caterpillar earthmoving and Atlas Copco rotary "down the hole" (or DTH) blasthole drills, both of which are supplied by exclusive southern African distributor, Barloworld Equipment. Together, they contribute towards the efficient extraction and haulage of the high tonnage volumes that Andru Mining is renowned for.


Andru Mining directors and personnel on site at Uitkyk together with Johan Kruger (bottom right) from Barloworld Equipment.

DRILLING EFFICIENCIES

Within this plant mix, Andru's Atlas Copco DTH rigs are a critical element in achieving production efficiencies, with two DM 30 units operating at Uitkyk and the other on a chrome contract in Boshoek, North West province. The typical overburden depth at Uitkyk is 32m.

"As with any blasting expectation, the fragmentation pattern has to be right the first time," explains Andru Mining director, Doug Troughton. "For example, at Uitkyk this is especially the case given the presence of clay bands and dykes, which add to the blasting challenges."

"In the past, we used to outsource this function, but the inconsistent results achieved led to Andru's decision to bring this service in-house, plus we wanted complete control in terms of safety," Troughton continues.

At Uitkyk, the DM 30's achieve a drilling depth of between 15 to 20m at a hole diameter of 165mm and a burden spacing of approximately 5m x 5m.

 

Andru Mining's recently acquired D10T in operation at Uitkyk. The proven elevated sprocket undercarriage on the Cat D10T isolates the drive train components from ground-induced impacts: the suspended undercarriage puts more track on the ground for higher traction and less track-slip.

CAT RIGID HAULAGE & DOZING

Supporting the DM 30's at Uitkyk are a range of Cat rigid trucks comprising six Cat 777F's with around 5 000 to 6 000 hours recorded (target payload around 90 tonnes), nine Cat 773F's (capacity approximately 55 tonnes) and a Cat 769 (with around 22 000 hours and a target payload of 35 tonnes). For Andru Mining these machines provide a perfect fit with the company's mining shovels. (The optimal target is a four pass match.) Haulage distances are in turn around 1,3km to the primary crusher; and between 500 and 600m for rollover prestrip.

This fleet was further bolstered by the acquisition of a Cat D9T and Cat D10T in 2009, which are dedicated to production dozing. All these Cat units are maintained by Barloworld Equipment's field service unit, based in Middelburg. Added to this support, Andru also has fully equipped workshops on site at all its mining operations to ensure that its preventative maintenance strategy is effectively managed.

Comments Andru Mining's plant director, Keith Reddy: "We opted for the Cat D9T and D10T dozers based on their world class track record, and their ability, when coupled with an optimal blast design, to achieve best-in-class production dozing. We also make use of Barloworld Equipment's trainers to keep our operator's abreast of the latest technological developments from Caterpillar.

"It's important that our machines perform to their designed capability, and in this respect operator training is vital. For example, we endorse the practice of slot dozing down hill and not further than 60m to maximise site performance and machine utilisation.

"Barloworld Equipment has also been instrumental in carrying out production job studies and site assessments on our haul roads, which have helped to reduce our working costs. Although Uitkyk's current pits, measuring 900m in length, present challenges in terms of the ideal 1:10 gradient, we work closely to this target, surveying every two months. We appreciate that this is critical for optimal cycle times and production efficiency."

Going forward, Andru Mining continues to build on its proud history. Founded by Terry Troughton, who remains a key figure in the business, Andru Mining was first registered as a construction company in 1979, operating mostly in the KwaZulu-Natal region. From the onset Andru was involved in the mining industry, deploying scrapers for stripping overburden. This now forms the symbol for Andru Mining's logo.

In the 1980's the company diversified into mining, establishing an office in Benoni in 1983. This subsequently led to a decision to focus 100% on mining from 1992/93. However, Andru has still retained its civils capability on mining related infrastructure projects for concrete structures, road construction and bulk earthworks. (Today, Andru Mining operates from its head office in Pomona.)

Adds Elphinstone: "We've come a long way in a relatively short period of time, with a proven track record that we're proud of. For example, one of our longest standing mining contracts has just come to a close, having run as a greenfields project from 1994 and ending in the third quarter of 2009: 80 000 tonnes of coal per month over a 15 year period.

"We've definitely earned our credentials as one of South Africa's foremost mining contracting companies, and we're well positioned with a reasonable order book going forward. As with the mining industry in general, we look forward to a renewed upturn in the resources market in 2010."

 

Fielding a comprehensive haulage fleet, Andru Mining currently deploys six Cat 777F's, nine Cat 773F's, and a Cat 769 at Shanduka Coal's Uitkyk mine in Middelburg.