KCM makes progress: After almost two years in operation under very adverse conditions, KCM is making headway and significantly raising production, as John Chadwick saw on a recent visit.
KCM is spending $270 million on refurbishment of all operations. Of this total, some $124 million is being spent at Nchanga Division, $77 million at Konkola and $8 million at Nampundwe. The remainder is for 'off-mine' projects and preliminary work on KDMP. This refurbishment is a huge task involving well over 1,000 separate contracts. By comparison, a new large mine might require about 100 contracts. Although extensive due diligence work was carried out by Anglo American prior to the purchase, such work cannot be expected to accurately reflect the refurbishment required. Once work started, some of the mines and plants turned out to worse than expected, while others posed pleasant surprises. Every facility was seriously under-capitalised. Both underground mines, for example, had hardly any developed reserves and waste stripping at Nchanga open pit (NOP) was well behind what was required. Much of the mining equipment (surface and underground) was in very poor condition.
Since then, Nchanga underground has exceeded expectations while NOP has been adversely affected by the accident (a major slope failure) that occurred in April 2001. Conditions were worse at Konkola mine than expected, but all concentrators have responded quicker than the mines. Their cost performance is going down with increased recoveries and better efficiencies and today they have spare capacity. KCM's concentrates are sent to both the Nkana (Smelterco) and Mufulira (Mopani) smelters, as well as cobalt concentrates to the Chambishi and Nkana cobalt plants. Smelterco was a huge bottleneck last year, but towards the end of 2001 the smelter was beginning to perform at expected capacity.
Because ZCCM had so little capital to spend in its final years, it took KCM six to seven months to re-establish its supply pipelines. That lack of capital also meant that certain aspects of what is today generally expected technology was not available to the mines. For instance, in mid-2001 KCM installed six CAD workstations at Nchanga and Konkola mines. Now the mines have an electronic information management system. Until then all engineering drawings were done manually. All existing manual and microfilmed drawings have now been converted into the electronic format
Because of all these problems, KCM has not achieved its targets for production in 2000 and 2001. The refurbishment has become a four-year, rather than three-year, programme. Annualised production in 2000 was 165,000 t of copper and the company has sought to increase output by 20% each year, rising to some 210,000 tin 2001 and 240,000 t this year. 2002 production is basically 60,000 t from each of the four production units -- Nchanga underground, NOP, Konkola and the TLP.
By the end of the 2001 third quarter, about half of the $270 million refurbishment budget had been spent and about two-thirds had been committed. There was concern that with all the work being done throughout the three divisions, certain areas of the mines and plants temporarily did not comply with Zambia's Mines Department's regulations. Dispensation has been allowed while the work is completed and a budget of $17 million is included in the total for complete compliance of all operations.
Despite the problems of 2000 and 2001, Tim Wadeson, who retired as chief executive officer at the end of 2001, to be replaced by Robin Mills, who was chief operating officer, told MM at the end of September 2001 that KCM "thinks it has taken $0.40/lb out of costs." He also pointed out some of the major achievements:
* An excellent management team
* A labour force that is well trained with an extremely well established mining ethic
* A very stable labour force, since they all now live in their own houses (debt free)
* A very mature and very helpful union
In general he noted that KCM had been welcomed by the work force since job security is better now than under ZCCM. And their safety is improving. Obviously, the figures do not look good because of the NOP fatalities last year, but even so the number of lost time incident (LTI) events is showing a strongly downward trend.
Nchanga underground is a continuous block cave, with the exception of the Chingola B orebody which dips at 100 and averages 8.5 m thick. Here, room and pillar mining takes the ore in two slices, using jumbos for development drilling and LHDs for loading and haulage. It only accounts for 18% of Nchanga's underground production but it is high-grade ore, averaging a 3.7% Cu head grade.
The block caving ore averages 25 m thick and is mined while maintaining the caving face at no more than 600. This method employs scraper drifts in a herring bone pattern with finger raises as drawpoints. Rings are drilled from trough drives in the solid footwall arkose just before caving is required.
Nchanga can hoist 2.8-3 Mt/y and at grades averaging over 3% Cu it could deliver up to 90,000 t of contained metal annually. It is expected to close in about ten years, during which time its output will be falling off.
NOP is much nearer the end of its economic life. It had been planned to continue mining copper and cobalt ores, and milling them, into 2003, with cobalt milling extending into 2004. This programme has been extended by a year due to the slope failure. Ten workers lost their lives in the accident and one P&H shovel, one blasthole drill, one dozer, one grader and one Land Rover were damaged beyond repair. A blasthole drill and two trucks were put back to work after repairs.
A group of geotechnical experts have examined all the pit walls since the accident, giving KCM data on risk levels. A major dewatering programme was immediately initiated. An extra 28 Mt of material has to be moved at NOP because of the slope failure. To achieve this extra capacity a number of used units have been purchased; two Caterpillar 992 wheel loaders, four Cat D10 dozers and five Komatsu 630 trucks. The latter joined the existing truck fleet of six Cat 789s, ten Komatsu 730s and 17 old Wabco Haulpak 120 t trucks. A Modular Mining Dispatch system is being considered to manage this fleet, other units of which include the F&H shovels, either 2300s with 19.1 [m.sup.3] buckets or 2100s with 11.5 [m.sup.3] buckets. There are five P&H GD120 blasthole drills, two Bucyrus drills, a 55R and 45R and one Ingersoll-Rand DMH. There are also 11 Caterpillar 33 [m.sup.3] scrapers and a Caterpillar support fleet of 994 and 992 wheel loaders, 834/824C rubber tyred dozers, ten DION track dozers and 11 16G graders.
NOP normally extracts 5.1 Mt/y of ore grading 2.3% Cu, along with 840,000 t of cobalt ore grading 0.45%. The stripping ratio is now 12.2:1 so about 65 Mt of material is moved annually. Mining generally moves from west to east, for two reasons; it is moving away from the underground operations and it allows waste dumping in the pit.
NOP's cut-off grade is 1% Cu so there are reserves left behind that could be processed in the future. However, the greatest potential for future surface mining, or rather dump rehandling is the Chingola Refractory Ore (CRO).
This is a resource of some 180 Mt at an average grade of 0.9% Cu that has been stockpiled at various locations within the Nchanga Mining Licence area. CR0 mainly comprises banded sandstone, Upper Banded Shale, pink quartzite and shale marker, some dolomitic schist and micaceous arkose. These formations, when grading above 0.5% Cu, are mined as refractory ore and stockpiled on designated dumps. Copper in these ores is contained in the mica lattice.
Mining of CR0 material will incur minimal costs since it lies in various dumps close to the East Mill where it would be crushed and milled. Ambient pressure, slightly elevated temperature (60[degrees]C) agitation leaching will be used to treat the refractory ores. Leaching in an autoclave has been investigated by Anglo American Research Laboratories in Johannesburg to treat copper flotation concentrates. The process is likely to include a pre-leach carbonate destruction step. The high grade leach process would link into the existing TLP. The current tank-house capacity will have to be expanded to accommodate the rise in production of cathode copper.
The high-grade leach process will yield an excess of acid, which has to be neutralised. However, treating the CR0 will serve as an acid sink and KCM considers that the copper recovered from this ore (possibly 30-35,000 t/y) will offset the treatment costs.
The TLP was originally commissioned in 1971. It has since been modernised and has undergone two expansions such that today it treats 18,000 t/d each of current (concentrator) and reclaimed tailings. Its nameplate capacity is 100,000 t/y of copper cathode.
Delkor Technik carried out one of the major TLP contracts refurbishing 15 Delkor horizontal belt filters. The belt filters were originally supplied by Delkor in 1984. Five mild-steel pre-leach filters and 10 stainless-steel leach filters had to be refurbished.
Konkola, the most northerly of the Copperbelt mines, is one of the wettest mines in the world. The Konkola ore body occurs in the Kirilabombwe Anticline. On the southwest flank of the antidline, the orebody averages around 9 m in thickness and dips 50-70[degrees] southwest. On the nose and north limb of the anticline, the orebody has an average thickness of 13 m and dips 10[degrees] west to 55[degrees] north. Reserves and resources have been defined to a vertical depth of 1,400 m and the deposit is still open at depth.
This mine has the capacity to hoist 2-2.4 Mt/y, but the long-term future of KCM rests on an expansion to 6 Mt/y, currently planned to be in place by 2007. It is served by No.1 and No.3 shafts, each with a nominal hoisting capacity of 1.2 Mt/y. No. I Shaft has its lowest tramming level at 950 m below surface. Its ore reserves will be exhausted in six to seven years. The lowest tramming level at No.3 is 590 m down and its ore runs out in three years.
Konkola has a well engineered water handling system. Every main level has a watertight door to protect the shaft and other major underground installations, and an elaborate system of water control and emergency water storage facilities has been established. These include five 1,552 [m.sup.3] sumps and five 1,662 [m.sup.3] settlers, drain drive penstock valves and surge barriers at No.1 Shaft. At present two sumps and one settler remain empty as emergency standbys. Four new sumps and a settler are being constructed as more water is expected as development proceeds north.
There has never been a serious water event at Konkola, but should there ever be one its effect, without all the precautions taken, would be disastrous. Prior to the installation of the extra sumps and settlers, Konkola had calculated that should the pumps fail it would take just 38 minutes to inundate the sumps and settlers. However, there would still be time to proceed with orderly emergency procedures but the watertight doors would have to be closed after about two-and-one-quarter hours.
The orebody is sandwiched between three aquifers. The main aquifer is a layer of dolomite lying just above the hanging wall, accounting for 40% of the flow. The footwall aquifer accounts for another 30% and then there is the lower porous conglomerate footwall quartzite. All major structures are developed in this quartzite, so it has to be dewatered.
Sub-level open stoping on retreat recovers the majority of the ore mined at the north end of I shaft's area, where the dip exceeds 30[degrees], so mining areas must be dewatered prior to stoping, to prevent massive water inrush. Dewatering is effected by boring drainage holes from special dewatering crosscuts driven into the hanging wall. Konkola aims to be a minimum of two years ahead on dewatering.
Current operations require pumping of some 300,000 [m.sup.3]/d. The water is of good quality, and the concentrator uses 50,000 [m.sup.3], some is treated and used as township water and the balance is pumped into the local drainage system. Pumping represents about 40% of Konkola's mining costs. No. 1 Shaft has pump chambers on the 370 m, 690 m and 985 m levels. All are interlinked in case of power failure and a 20 MW diesel generating facility will take over in case
of power failure from the national grid.
Mr Mills noted that KCM found that conditions were worse at Konkola than expected.' The most serious problem was the lack of developed reserves. Catching up on development is included in the total refurbishment budget. In addition to development, all the track work (some 20 km) has been refurbished and work has been done on the shafts and the ventilation system such that all are now up to the proper standard.
Under ZCCM, main level dewatering development had been ceased for some years and some boreholes had been shut to save pumping costs. A Shaft Sinkers/AMCO joint venture was awarded the contract to recommence dewatering. Similarly Skanska (Cementation) was awarded a contract to sink a 5 m pipe shaft for increased pumping capacity, and is carrying out a substantial sub-level development contract.
Drawpoint loading has been introduced to the mining areas of both shafts. Two suppliers were selected to provide the LHDs, Caterpillar Elphinstone at No. 3 Shaft and Sandvik Tamrock Toro units at No.1 Shaft. Both manufacturers have embarked on maintenance and repair contracts (MARCs) and are providing training for both operators and KCM mechanics. Barloworld, Caterpillar's southern Africa dealer, maintains the two Elphinstone Rl600s and three Rl300s at 3 Shaft,
Open stoping with scraping is the main mining method at No.3 Shaft and mechanised overcut and benching has been introduced, using a Tamrock Solo, which Robin Mills says is "looking good." At No. 1 Shaft, there is a shift from sub-level open stoping to longitudinal room and pillar methods.
Before the Solo 05 was delivered to Konkola, Sandvik Tamrock Zambia undertook an important study and worked out drilling costs for KCM. The company undertook to guarantee 60 m of drilling per percussion hour with the Solo, compared with KCM's average of 7 m per percussion hour using bar and arm machines. Sandvik Tamrock committed to a penetration rate and a drilling cost.
Konkola No.3 Shaft's Solo 05 is part of a very unusual contract. Sandvik Tamrock Zambia is actually managing the machine for the first six months. In this way it can ensure that the entire infrastructure is in place for this machine to give of its best. It is a process engineering project as well as being a drilling project. Gary Hughes, Sandvik Tamrock Zambia's country manager explains, "when we hand over the machine, the Konkola people involved in its future operation will know what the standards are that need to be upheld." There is an operations instructor on every shift for the six-month initial contract. This Solo is drilling both downholes for bench drilling and upholes and is operating at well in excess of call.
The Sandvik Tamrock MARC at Konkola began with two Toro 400Ds in 1999 and now also includes four 007s and one 006. All Sandik Tamrock Zambia MARCs operate with 2.8 persons per machine. The machines are stopped for one hour every day for daily checks. A comprehensive service is conducted every 125 hours, with more comprehensive services every 250, 500 and 1,000 hours. Availabilities average 89-92% and the machines will operate up to 12-15,000 hours before being rebuilt. The actual hours before a rebuild are the customers choice, and sometimes they go longer. Though availabilities are good, the next aim on this MARC is to get utilisation up from the current 30-35% to 65%.
Each Sandvik Tamrock MARC in Zambia is run as a business with a dedicated contract supervisor who is responsible for the profit and loss. In addition to the Heavy Equipment Repair technicians working on each MARC, each one has a planner/scheduler who, amongst other things, ensures that parts get to site and underground when needed. There is also a foreman who has chargehands, one each on backshift and dayshift, monitoring and overseeing all work underground. A data input clerk does performance reporting and organises all maintenance routines.
Tyres and road maintenance are also included in this KCM LHD MARC. KCM has purchased two Veekmas underground graders and one is in operation at No.3 Shaft. At present a Sandvik Tamrock Zambia operator is using this machine, demonstrating best practice in road grading to maximise tyre life. Similarly, the contract is operating with local tyre supplier, Quality Tyre. That company supplies the tyres and Sandvik Tamrock personnel manage them, serving all tyre needs. Tyre life has risen from 450 to 650 hours, and should increase further. Tyre downtime is now included in the mechanical downtime on the LHDs at Konkola. Even so, the Toros' machine availability is still at least 89%, thanks to proper preventative tyre maintenance.
All the KCM Toro LHDs have been equipped with remote controls to increase safety in drawpoint loading, and training has been given in their use. Also, they are all being equipped with Tamtron on-board weighing systems. These allow Sandvik Tamrock to provide mine management with production analyses. These Tamtron units provide dynamic weighing with an accuracy of 0.5-2%. Weights are calculated based on the measurement of pressures in the hydraulic lifting cylinders. The weight measurement is completed while the LHD lifts its boom to dump its load.
The Konkola Deep Mining Project (KDMP) will boost mine production to 6 Mt/y at the end of a five-year construction and production build-up period. The average mill grade over the life of KDMP is expected to be 3.8% Cu. Copper cathode production from the treatment of Konkola concentrates will increase from its present level of some 55,000 t/y to a peak of 220,000 t/y at full output. Finished copper output is forecast to exceed 200,000 for a period of some 20 years. Over the life of KDMP, some 5 Mt of finished copper will be produced. Cobalt will not be produced as it is not commercially viable, nor is any other byproduct. Ore reserves have been estimated at 120 Mt grading 4.33% Cu, with an additional 61.4 Mt in the resource category grading 3.09% Cu. The orebody is open at depth and the eventual life of KDMP could be well in excess of 20 years.
If KDMP receives board approval, the current mining methods will be changed to pre-dominantly cut and fill methods, which will significantly reduce dilution. KDMP must have 80% of its voids filled with hydraulic backfill. Already a backfill plant has been commissioned, last November, for the existing 2 Mt/y mine. This uses currently generated tailings, of which 40% can be cycloned out. A much larger plant will be required for KDMP, probably with cement addition to the tailings. In-house Anglo American experience with backfill will play a large part in its design. Some 2.1 Mt/y of coarse tailings from a new concentrator will be used in the backfill for KDMP.
The cut and fill methods to be employed at KDMP will result in a significant reduction in dilution and improved recovery. The average stoping dilution is expected to be 14%.
To provide the No.4 shaft for KDMP, the existing VS3B upcast ventilation shaft will have its finished diameter increased to 10.74 m and it will be deepened from its current depth of 594 m to 1,488 m below surface. It will be equipped with two 3.7 MW friction winders for hoisting ore, a 2 MW double-drum men and materials winder and a single-drum service winder. It will have four 23-t capacity skips able to hoist 6 Mt/y of dry ore and 1.2 Mt/y of waste rock.
A new pump station will be constructed on 1,380 m level to handle all the water from below 950 m. Settled water from here will be pumped to 345 m, 660 m and 950 m via the rising mains in the emergency access shaft. The water will then gravitate to the existing 370 m, 690 m and 985 m pump stations at No.1 Shaft. The latter pump station is to be expanded as part of the project. Pumping is likely to increase to 400,000 [m.sup.3]/d.
Two new 5.7 m diameter upcast shafts (VS4A1 and VS4A2) will be raisebored from surface to 800 m. No.4 Shaft will become a downcast and provide all additional intake air.
A new twin-module concentrator will be constructed and the existing plant will be decommissioned. SAG and ball milling will provide a 90% minus-74 micron feed to the sulphide and oxide circuits of the flotation plant. Average recovery at the new concentrator is estimated to be 89%. Concentrate will be railed to the Nkana smelter and refinery for treatment, with copper recovery estimated at 96.4%.
The life of project C1 (Brook Hunt definition) cash cost of production is expected to be $0.50/lb of finished copper, at mid-2000 money value. Using the same money value, the capital cost of construction and commissioning of has been calculated at $600 million.
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|Title Annotation:||Konkola Copper Mines|
|Article Type:||Statistical Data Included|
|Date:||Feb 1, 2002|
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