Thompson – The other INCO

Inco Ltd. is spending heavily to secure its future in Thompson, Man. In addition to the C$108 million already committed to the 1-C orebody at the main Thompson mine, Birchtree reactivation and the Thompson open pit, the new investment of $287 million brings the total to very nearly $400 million. It also means that Inco will have invested a total of $1 billion in Manitoba since the orebodies were discovered 30 years ago.

The greater part of the new investment, $209 million will be spent developing the 1-D orebody, an extension of the structure to be worked through the Thompson shafts. It will consist of three new, 3,700-ft. (1.1-km) shafts and three miles of automated rail haulage to connect the new workings to the existing Thompson shafts.

The remaining $78 million will be used to complete the re-development of the Birchtree mine, including deepening of the shaft to 4,250 ft. (1.3 km) and supporting works to bring production to the targeted level of 4,500 tons (4,090 tonnes) per day. The net result of this massive financing will see Thompson’s nickel production maintained well into the 21st centnty. At 100 to 110 million pounds of nickel per annum, Thompson will contribute more than one-quarter of Inco’s total worldwide output.

THE NORTH AND THE SOUTH

Within bow shot of Inco’s main office and mill/smelter complex are the two Thompson open pits — the North pit, very nearly exhausted after the mining of 5.4 million tonnes at an undisclosed but presumed grade of about 3.0% nickel, and the South pit, now stripped of overburden and moving into production. Here, reserves are estimated by The Northern Miner Magazine to be in the 3.2-million-tonne range and grading about 2.5% nickel. Both pits are on the Thompson mine’s crown pillar, which roughly constitutes a reversed “S” shape, with the central straight stretch essentially barren and the upper and lower “hooks” occupied by the North and South pits respectively.

Small lakes and a major volume of sands, silts and gravels occupied the site of the two pits, so Inco made the decision to strip the overburden by dredging. This was not a new experience for the company, the Pipe Lake open pit having breen dredged in the mid 1960’s, and there were no reservations about using the method again. Incidentally, the Pipe Lake mine, 35 km southwest of the town of Thompson, was closed in 1984, but the orebody is far from depleted and production is scheduled to resume (from underground) in the early years of the 21st century.

Dredging of the North pit started in August, 1983 and was completed 45 months later after removing about 22 million cu. yds. (16.7 million cubic metres) of material. Dredging of the South pit was on a smaller scale, with the more than 5.5 million cu. yds. (4.2 million cubic metres) of material having been cleared by May, 1990 after a 12-month campaign.

Dredging in both pits was planned for continuous operation with provision for a winter shutdown if necessary, which, in the South pit, amounted to three of the 12 months. The dredge itself is a 138-ft. (41-metre) scow fitted with lifting booms, mooring spuds, a 10,000-hp pump for moving the liquified overburden, and an 11-ft. (3.3-metre) cutterhead capable of reaching to a depth of 35 ft (10.5 metres). The dredged slurry was pumped to an existing tailings dam about six kilometres away through a 42-inch (106-cm) pipeline.

An interesting aspect of the operation involved the removal of the dredge when stripping had been completed. By the time stripping was finished in the North pit, the dredge had lowered itself to an elevation of 150 ft. (45 metres) below the level of the surrounding country. The problem was to move the dredge up an 8% access ramp and out of the working area. In due course, this was carried out using a 100-ft. (30-metre) trailer, rolling on no fewer than 288 wheels, cradling the dredge’s 1,200-ton deadweight, and the whole inched forward by an assemblage of haulage trucks, bulldozers and loaders, 3000hp in all. The physical task of moving the dredge took no more than 30 minutes; the planning of the lift and the move, six months.

The glaciated surface of the bedrock that is exposed after dredging is deeply scored with narrow gulleys (far too narrow for the dredge’s cutterhead to enter) and innumerable dips and hollows still filled with glacial sands. Before open-pitting can proceed in earnest, all of the residual sands and gravels must be dug out with small, mobile loaders. The rock surface must be trimmed of its ridges and humps to permit passage and provide a stable base for the blast hole drills. At the time of our visit, the preparatory rockwork was being carried out with air tracks operated by company employees. A local Thompson contractor was busy cleaning up glacial debris and trimming overburden push-backs. A total 1.3 million yards (1.2 million metres) of unconsolidated material is involved here.

Sharply Defined Zones

The open pit orebody is by no means a wide, regular body of massive sulphide. Most of the mineralization is in the form of discrete, well-defined bands of disseminated sulphide within a mica schist or quartzitic host rock, and it is roughly conformable with the formation. Despite the disseminated mode of occurrence, the zone of sulphide is sharply defined and there are no assay walls as such. Ultramafic species may compose the wall rock from time to time and at Birchtree, peridotite has considerable local imporatnce.

The orebody is irregular both in plan and section and is frequently braided in form with lens-like inclusions of country rock and, conversely, lenticular concentrations of disseminated ore which resemble nearly massive sulphide. It is these characteristics which presumably led Inco to adopt cut-and-fill stoping when underground mining at Thompson first began.

The North pit finished with a length of 5,000 ft. (1.5 km), a maximum width of 800 ft. (240 metres) and a depth averaging 350 ft. (105 metres). The South pit will be substantially smaller and will leave a final pillar of 60 ft. (18 metres) between the pit bottom and the uppermost underground workings.

Clay and Fabric Installed

A section of the North pit was mined through to connect with the underground workings because of the high-grade nature of the ore at that point and ultimately led to the installation of a massive impermeable seal of puddled clay and fabric when mining had finished in the pit.

Open pit mining will follow on the lines previously practised in the North pit: 40 ft. (12-metre) benches drilled off on a 20 x 20-ft. (6×6-metre) pattern using 9 7/8-inch holes up to 45 ft. (13.5 metres) in length. Blasthole drilling will be by two Bucyrus-Erie 45R machines and the muck loaded by a leased Hitachi EX 1800, 13.5-yd. hydraulic shovel, two Caterpillar 992 loaders (also with a 13.5-cu.-yd. capacity) and two veteran Marion 151 rope loaders with an 8-cu.-yd. capacity. Both of the latter machines have been active since the early days of Pipe Lake and are now being allowed to run themselves out to a standstill. The haul to the 54-inch gyratory crusher is a short one (three-quarters of a mile at the most) and is carried out with a fleet of six leased Caterpillar 777 trucks, each with an 85-ton capacity.

In addition to the above-mentioned major items are the numerous smaller loaders, dozers, graders, service vehicles etc., without which any pit would rapidly come to a standstill.

Good Timing

Whereas an underground mine usually requires years of heavy investment to reach maximum production, a developed open pit can be turned off and on practically at will to meet the particular production requirements of the day and this, without any noticeable impact on the size of the workforce. In the case of the North pit, the deposit came on stream just as nickel prices were starting on their heady climb to C$8 per lb. — an entirely fortuitous happening. One might even suspect the workings of the hidden hand, a reward for having made the original investment during Inco’s bleak and pinched days of the early 1980s.

BIRCHTREE: SETTING A STANDARD

The Birchtree nickel mine, about 5.5 km west of Thompson’s T1 shaft, was the second underground mine to be opened by Inco and produced more than 6.6 million tonnes from 1969 to 1977. It then stood idle for 10 years while the Pipe open pit picked up the balance of the mill’s requirements. In 1988, Inco embarked on a C$58-million, 5-year development program and recently increased to a total of C$136 million, with the ultimate objective of producing about 4,500 tons (4,090 tonnes) per day by 1997. Dewatering started in 1988 and underground production has been gradually increasing as more working places become available. Current production is 1,800 tons (1,640 tonnes) per day with a total payroll of 160 men, including staff and 40 contractors. When full production is reached in 1997, underground productivity will reach 28 tons (25 tonnes) per manshift, which is four times the mine’s production rate during its cut-and-fill days in the 1970s.

Interestingly, when the mine was allowed to flood in 1977, the water was not permitted to rise above the 1,500 ft. level (450 metres). The reason was to prevent the sand fill of the stopes from becoming saturated and building up the hydrostatic head that would have collapsed the drift support and engulfed a large part of the mine in sand.

The mine was originally developed by a 3,335-ft. vertical shaft, with 11 levels at 200-ft. (60-metre) intervals. If current development plans are executed in their entirety, the shaft will be deepened to 4,170 ft. providing an additional 11 levels at 150-ft. (45-metre) intervals, with the last being at 3,900 ft. (1,170 metres).

The biggest change in store for Birchtree, and the change that will see a quadrupling of productivity, will be the replacement of a rail-bound, cut-and-fill mining method by a fully mobile, blasthole open stope system. This is the plan, but for some time, and at least until mining has progressed well below 2,100 ft. (630 metres), there will be a hybrid consisting of a rail system above that level and a trackless system below. The mine’s present ramp is collared 70 ft. (21 metres) above the 2,300-ft. (690-metre) level and therefore all vehicle maintenance must be carried out underground.

Tricky Transportation

There is also the time-consuming and tricky task of bringing the mobile equipment down from surface in the first place. Fortunately, Birchtree’s shaft is “square” rather than rectangular in section (common to many mines) with a correspondingly large cage compartment. Nevertheless, most equipment must be dismantled to a greater or lesser extent and quite frequently flame-cut. These inconveniences may infact be short lived and the ramp is expected to be carried through to surface in due course.

As described earlier, the ore is far from consistent. It not only flexes and varies in width but also encloses lenses of waste rock of varying dimension and tends to shoot spurs of mineralization into the walls. Mining this type of mineralization and maintaining a planned grade at the same time is no easy task and entails balancing the high productivity of a blast-hole open stoping system against the lack of selectivity of the same system.

Reserves to the 3,950-ft. (1,185-metre) level are estimated at approximately 2% nickel with negligible copper content and will keep the mine in operation over the next 20 years. The orebody is cut off by a strike fault below the 3950 level and what lies beyond is unknown.

Because of the variability of the ore, a standard mining layout is not practical and each ore block must be considered separately. Diamond drilling may recommend a wider sublevel spacing than is applicable elsewhere and the presence of a narrow, low-grade section may be the obvious location for a stope boundary pillar, rather than some arbitary distance along strike. Allowing for the uniqueness of any given stope, Birchtree’s mining plan hinges on a series of sublevels spaced 70 to 150 ft. (21 to 45 metres) apart. These serving as drill bases for rings of fan or sub-parallel blast holes with the holes breaking into a slot developed from a 42-inch-diameter raise borer hole. Broken muck is loaded through drawpoints of the larger tonnage stopes or via remote-controlled loaders entering the stope itself. In these latter stopes, the volume of ore is too small to justify the driving of a separate mucking drift and the open stope itself is the drawpoint.

A greater part of the mine’s present lateral development is carried out by contractors, but this is expected to change as Birchtree’s own labor force grows. In this mine, Alimak raising will be in limited use, because of the large excavation needed for collaring the raise and storing the Alimak itself and it is expected to develop most of these openings by raise borer. Already, a number of 42-inch-diameter raises have been drilled on a test basis using a Robbins Mini RB40 borer and the performance has been encouraging. Not the least of the advantages are improved safety and the capability of setting up the machine in a standard, 13 x 13-ft. (4 x 4-metre) drift opening.

Drift support is by mechanical bolts in the back and split sets in the walls, pinning a heavy-gauge, 4 x 4-inch fabric (WWF) to the rock surface. Bolts are eight feet (2.4 metres) wherever the span is greater than 12 ft. (3.6 metres); and where rock conditions demand, resin-bonded bolts 16 ft. (4.8 metres) long are interspersed among the shorter bolts.

The rock walls and back stand very well and there does not appear to be any obvious reason for the extensive covering of WWF, which is draped down to about shoulder level. However, these are fresh openings and once stoping has reached a mature stage, the schists and quartzites start to adjust to the stresses and loose walls, and the back can develop quickly. The preservation of sound rock surfaces is assisted by the creation of stable surfaces in the first place, and perimeter blasting is practiced extensively. Back and shoulder holes in the drifts are drilled about 18 inches (46 cm) apart and blasted with “Powertrain,” a small-diameter explosive that air-cushions the blast and minimizes fracturing. It is manufactured by ICI Explosives.

Stope and development mucking is accomplished by a fleet of Eimco Jarvis Clark diesel load-haul-dump machines including 2.5-, 3- amd 6-cu.-yd. units, and one or more JCI 8-cu.-yd. loaders are planned. There are three Eimco Jarvis Clark 426 trucks underground now, and when the mine is in full production, there will be eight or 10. One of the new JCI 2604s, still on surface at the time of our visit, has been shop-cut and fitted with bolted splice plates to simplify its breakdown for lowering down the shaft.

Down-the-hole ring drilling is carried out with two CD360 drills manufactured by Continuous Mining Systems, an Inco subsidiary. These drill 4.5-inch holes at an average rate of 150 ft. (45 metres) per shift. In addition, there are two conventional Gardner Denver 123 rigs and two Boart longhole drills mounting Seco Mk 5 drills. What could shape up to be a significant longhole machine recently arrived on the property. The Gardner Denver GDC1H “top hammer,” which is essentially a miniturized open pit blast hole drill, has the potential for drilling 250 to 300 ft. (60 to 90 metres) per shift with a minimum of deviation. (For details, see page 28 of this issue.)

As noted, mobile haulage utilizes 24-ton trucks and the present rail haulage consists of 9-ton battery locomotives drawing trains of 5-ton Granby cars. One of the major innovations at Birchtree will be the automated rail haulage system on the 2,100-ft. (630-metre) level. When full operation is achieved in December, 1991, the system will be 3,000 ft. (900 metres) in length. A single operator in a remote console will see to the loading of five 247-cu.-ft. roller dump cars, haulage to the dump, operation of the crusher and discharge of the crushed rock into the skip loading pocket. It is logical that the same operator be used for controlling skip loading and hoisting, and that stage has been tentatively scheduled for 1995.

Another innovation for Birchtree will be the use of cemented rock fill rather than the consolidated sand fill of the Thompson mine. Crushed ore from the headframe bin is trucked 5.6 km to the Thompson mill and crushed waste rock will be returned on the back haul. Nominally of 10-inch maximum size, the rock will tend to degrade during its passage through the mine’s fill passes, producing an ideal, graded aggregate with a maximum cobble size of six inches. The aggregate will be drawn off at any given level by 26-ton trucks and sufficient cement slurry added to make a 4% mix. The final product is expected to produce a 400-lb.-per-square-inch fill, which compares dramatically with the 35-p.s.i. condsolidated sand fill of the Thompson mine.

Birchtree will implement automation to the greatest practical degree and the mine’s performance will be watched with close attention. For Birchtree is no ordinary operation; it is a difficult orebody to mine and the ore will be extracted at the healthy rate of 4,090 tonnes per day. Its performance will be a bench mark from which to judge Inco’s other deep orebodies. The future of Thompson may in fact be influenced by the response of this one operation to the impact of modernization.

INCOS CORPORATE CO-OPERATIVE

Commentary by David Scott

The inexorable shrinking of the gap between mining costs and revenues is nothing new to Canadian mining. The jackleg displaced the leyner, ammonium nitrate did away with nitroglycerine explosives, load-haul-dump machines succeeded rail-bound bucket loaders, and so on. If it seems that new technology is adopted in fits and starts with lengthy lapses following intense periods of innovation, well, this is perhaps the nature of the business. Of greater concern is the nature of these costs and their seemingly irresistible upward surge.

Wages and salaries are the most obvious contributors to rising costs. Then there are the ever-increasing demands from all levels of government and the myriad items that make up our standard of living. As a nation grows and matures, the standard of living of its people also improves and the general cost level is inevitably notched upwards. Western nations automatically opt for technical solutions to the problem of increasing costs — bigger, more sophisticated machines designed to generate a larger output from the same amount of labor. Logic suggests that the time will come when the costs of the ultra-sophisticated machine of the future will no longer be exceeded by the extra production it creates. Inevitably, this leads to diminishing returns. This indeed has already occurred. The most dramatic examples are the U.S. steel industry, once the world’s largest, and British shipbuilding in days passed. Experts may contest the details of these two examples, but in each case the cost of introducing new technology coupled with the then-current wage levels added up to an insufficient profit margin. The point of diminishing returns had been reached.

By and large, the Canadian mining industry has some distance to go before it enters the danger zone, but danger does exist. The question is, How will the industry put off the inevitable day when only a handful of unique operations will survive?

Already a few progressive companies in Canada are finding solutions to the problem of climbing costs, and they are finding it in their employees — an obvious place to look, one would think, but despite the usual message in the annual report thanking employees for their dedication and hard work, there has rarely been any deliberate effort to involve workers in shop floor consultation.

Of course, for management to consult workers runs counter to corporate tradition. But management is not alone in having to cope with such changes. Unions, too, have strong reservations, and they are suspicious of any attempts by management to recruit their members into schemes outside the employees’ normal field of activity. They regard such an approach as divisive and capable of undermining union organizations. For many years, government agencies and management consultants have tried to sell the idea of employee think tanks to corporations. Sometimes they have been successful, at least insofar as they have found the ear of upper management. But most of the resulting programs have generally expired at an early stage with, I am sure, audible gasps of relief from all concerned.

The reasons for failure are not hard to deduce: management has been generally sceptical (“No one has ever seen one of these programs work before”) and there is a concern that if employees are asked to analyze their own jobs and working environments, they will inevitably undermine their supervisors’ authority. This is a short-sighted view as supervisors, managers and senior executives are selected not so much for their technical knowledge as for their organizational and leadership skills.

Besides union misgivings, employee participation programs are prone to failure because of apathy among workers. Too often, think tanks, or participatory decision-making programs, are promoted as a means of reducing costs, for improving the company’s “bottom line.” But this approach is unlikely to stir enthusiasm among workers in large corporations; more than likely, it will leave them quite unmoved.

Achieving Self-fulfillment

How corporate executives would love to be able tap the energy and pride in workmanship that the employee generates when he leaves his workplace and takes up his favorite sport or hobby. The key to bringing this about is that there be a real sense of involvement and an opportunity for workers to achieve self-fulfillment. How to convey this opportunity to a group of understandably skeptical employees in a company setting is, without doubt, the most difficult hurdle to overcome. An understanding of think-tank processes is not difficult to transfer. The mathematical tools are fairly straightforward, consisting of the analysis of data by the use of graphs, histograms, frequency curves and the like. But instilling the enthusiasm and motivation to use these processes is another matter entirely.

The Inco of a few years ago typified the North American industrial corporation. Large and impersonal with a command-style management, it was not a fertile field for enthusiastic employee involvement. In recent times, a dramatic change has taken place, and for a case history in think-tank practices and employee participation, Inco’s Thompson division in Manitoba is the place to visit.

Inco introduced its think tank as an endeavour in the pursuit of quality about four years ago and it is now beginning to have a major impact. These programs entail a restructuring of management-employee relations and a change in traditional perceptions, all of which require a great deal of time to bring about. The circumstances are akin to an arranged marriage between people who had never met and time is needed to effect the transformation.

Active Leadership

The changes require the full support of senior management and they require the leadership that can only come from that same source. In Thompson’s case, leadership comes directly from Lorne Ames, president of the division. This is not nominal leadership but active participation, involving a considerable commitment of time and an understanding of human motivation — not to mention resilience. For it is not just a matter of moving the whole assemblage off top-dead-centre once. It has to be so moved over and over again until those involved can take control for themselves; after four years, this is beginning to happen.

The two basic underpinnings of any think tank program are the direct and energetic commitment of senior management and the employees’ awareness that there can be more than eight hours to the job, that there can also be personal involvement and the satisfaction that follows. Any good business deal has two winners and this is the way to achieve it.

SIDEBAR

A LOW-KEY STAKING RUSH

One of the most celebrated staking rushes in Canadian history took place near Elliot Lake, Ont. in the early 1950s when Preston East Dome, the seed from which Rio Algom eventually rose, staked most of the Blind River uranium belt. Hundreds of claim-stakers moved in at dawn, lawyers waited at the offices of mining recorders, doctors were on hand in case of accidents, and a fleet of helicopters was pressed into service.

Yet in Manitoba, at roughly the same time, a far greater staking — 130 km long by 13 to 16 km wide — had been completed. Almost an entire greenstone belt, yet barely a whisper to be heard. Even to this day, few people are aware of this staking rush, but then this is Inco’s way.

Since those early days, more than 68 million tonnes of ore have passed through the mill at Thompson, Man. Over the next quarter century, at least another 18 million tonnes will be contributed by two new operations, Birchtree and the South open pit. The South mine is a short-term pit and Birchtree is an underground operation.

SIDEBAR

QUALITY CONTROL

Dale Carnegie produced one of the most notable books in North American business history in 1938. How to Win Friends and Influence People was directed at the salesman in each of us and it is still current. Dr. W.E.Deming, an American, has also written a book, and chances are he will enjoy the same fame and prestige that greeted Carnegie. Ostensibly about quality control, Dr. Deming’s book was actually directed toward nothing less than corporate America. Deming is credited with helping Japanese business recover from the Second World War and his basic message to management is, “Improved quality of process automatically improves productivity.”

Inco introduced the system in 1986 at Thompson as “Statistical Process Control” (SPC), an awkward title, intimidating to some and consequently referred to as “think tanks.” The principle of the method is simple: Define what the problem is and determine the corrective measures, what will they cost and how will they be implemented. At Thompson, Inco has more than 200 “process improvement teams,” each made up of a group of employees, and they will be investigating a specific problem area or an opportunity for improvement, in their own department. They will employ common statistical and graphical techniques, scatter diagrams, histograms, Pareto charts, and so on. They will be able to call on expert help whenever it is required. Co-ordinating committees come into action whenever a problem appears to have fallout over a number of departments. Update meetings are held frequently to let everyone know what his neighbor is doing. People involvement is the key; people are the yeast in the dough.