The second IPCC Conference was held from 24-26th October 2012 at the Grand Hyatt in Bali, Indonesia. It was a major success not just due to the quality of the presentations and the fact that there was an almost equal representation from the key equipment OEMs and the region’s mining and engineering groups – but also because there was a real need for a specific event on this topic in this part of the world. Indonesia arguably has one of the mining industries which could benefit the most from widespread application of IPCC both due to the scale and nature of its world class coal deposits. Key mining groups from Indonesia, India, Papua New Guinea, Thailand and elsewhere in the region were able to get the contacts and technical overviews they needed to pursue new IPCC studies and project reviews. Where they had already looked into IPCC as a possible option, it provided thoughts on alternative routes and options that may not have been previously considered.
The following article principally summarises some of the main points that were made by the key OEMs in the presentation line-up – the remaining presentations from consulting groups and mining groups will be covered in a future issue. Two further papers on gearless drives for conveyors from ThyssenKrupp/Siemens and Takraf/ABB were summarised in the IM December issue on German Technology, as was a heavy haulage Tractomas solution from TII Sales.
In addition to the presentations below, Dos Santos International pointed out that its customers have recognised that its Sandwich Belt High Angle Conveyor is potentially a vital link to optimise many IPCC systems, linking the face operations with the pit perimeter and spoil operations “along the most efficient, most direct path.” In one particular development a reversing UHAC (Universal High Angle Conveyor) was employed to elevate or lower the crushed overburden to or from different levels depending on whether the spoiling was to an external dump area or to backfill areas of the mined out pit.
Joe Dos Santos, President of the company commented: “I have said that the second ‘C’ of IPCC has been largely ignored with the latest systems continuing to use conventional conveyors that are ill-suited to the in-pit haulage function. Due to the low angle limitation, excessive excavation and/or numerous transfers are required to get from the pit bottom to the surface. The maximum conventional conveying angle of 18° and gearless drives do nothing to change this unsuitability.”
Indonesia insights
The meeting kicked off with a presentation from Jeffrey Mulyono, President Director, PKN Coal and a former Indonesian Coal Mining Association (ICMA) Chairman. He referred to the scale of the coal industry in Indonesia, with total coal resources of 161,000 Mt and reserves of 28,000 Mt. Current thermal coal exports for 2012 stand at 230 Mt but are expected to rise to 250 Mt by 2014 – this puts Indonesia as the largest exporter by far – in 2012 Australia exported 160 Mt. On average, mined coal production has grown by over 34 Mt each year between 2004 and 2011, with exports growing at over 30 Mt/y and domestic consumption by 4 Mt/y. By 2015, demand for thermal coal within Indonesia is expected to rise to 96 Mt, with a 15 Mt demand from the cement industry, and 38.3 Mt from other industries. According to the optimal national energy diversification program, by 2025 electricity from coal will account for 32.7% of Indonesia’s energy requirements. Indonesia’s total production is predicted to reach 400 Mt in 2013; and even if 200 Mt of this can be mined using IPCC methods, the reduction in haulage cost would be huge, without even taking into account environmental benefits. In addition, if the average stripping ratio is assumed to be 5:1, which is typical for the country, then 2 billion bcm of overburden must be annually removed – assuming that some 40% of this can be economically transported using conveying systems, then about 800 million bcm will be diverted from conventional truck haulage. These volumes are large enough for IPCC to account for a “material movement revolution” and corresponding reduction of operating costs in Indonesia.
This was followed by a review of the new Mining Law in Indonesia by Mangantar Sabungan Marpaung, a Mining Strategist but formerly the Chief Indonesian Mine Inspector for Coal and Minerals until 2011. He pointed out the basic reason for changing the regulation, in that the old mining law from 1967 was deemed to be no longer suitable and that a revision of laws and regulations was required “in order to manage and seek potential minerals and coal in independent, reliable, transparent, competitive, efficient and environmentally sound manners to sustainably assure national development.” The goal is to assure legal certainty in the conduct of mineral and coal business activities, especially to clarify the roles of the central government, provinces and regencies in the mining industry.
MMD’s unique Asian experience
MMD Managing Director in China, Victor Lang focussed on its track record of successful deliveries of IPCC systems, with its focus on verifiable installations that use its sizing technology. MMD has delivered a large number of semi-mobile systems to Asia including multiple projects at Mae Moh, Pingshuo, Zhungeer, Datang and elsewhere, with 12 additional orders (both semi-mobile and fully mobile) in process. In fact of the 80 semi-mobile sizer stations installed by MMD between 1990 and 2012, half have been in China, by far the largest number, followed by Colombia at 12. Nine semi-mobile sizer stations will be delivered to Hongsa in Laos by 2015, with two more going into operation at a Banpu mine in Indonesia.
In the same period, MMD has delivered 11 fully mobile sizer stations, by far the most from one manufacturer. At China Coal Energy’s Pinghsuo East Surface mine, double working face fully mobile IPCC will be conducted using the new MMD Low Profile Sizer Station. Some 20 Mt of overburden will be removed initially to access 20 Mt of raw coal which will be mined using semi mobile systems. The fully mobile mining plan includes an additional face conveyor with mining side belt bridge in place of a belt wagon. The face conveyor will be moved 80 m every four cuts; with the active mining face measuring 18 m in height and 20 m in width.
The long term relationship between MMD and key mines was also highlighted, especially with regard to repeat orders. At Mae
Moh in Thailand, MMD delivered three 4,500 t/h sizer stations in 1993; followed up in 2002 by four 5,500 t/h sizer stations – and all seven are still operating, while other installations from other manufacturers have been removed. The second delivery was part of Mae Moh Phase 5, and these stations feed two 14 km parallel fixed conveyor systems, fed by two movable conveyors, the power for each system being provided by a 20MW power station. The contract called for 5,500 operating hours per annum and stipulated that the availability of the sizing stations be no less than 90%. A single conveyor system is able to handle the output from three and if required even all four sizer stations.
Three hydraulic shovels with 16m³ buckets each load three 100 t trucks with a haul distance to the sizer staions of a maximum 700 m and an average cycle time of eight minutes. Twin truck bridges allow two trucks to tip simultaneously. To produce the full 22,000 t/h involves 40 truck drivers per shift, four spreader operators per shift, 14 conveyor station operators per shift and 13 shovel operators per shift. The sizer stations are usually moved once a year, handling +/-18 million bcm between moves. Routine relocation of a system takes 3 to 7 days, however if necessary a sizer station can be moved in a day.
For fully mobile systems, MMD’s Goonyella Riverside project in Australia from 2001 onwards was given as a key example, though the new MMD LPMS at Pinghsuo will soon be operational. The Goonyella MMD ‘MS1’ 10,000+ t/h system is a fully mobile slewing sizer station, loaded with overburden by a P&H 4100A rope shovel loading directly into an MMD sizer which feeds a conveyor system with a design capacity of 10,000t/h which feeds the spreader. The MMD MS1 sizer station is capable of travelling at a speed of up to 12 m per minute and traversing a gradient of 10%. The machine was in operation for six years during which time a lot was learned that contributed to the development of the LPMS. First, that the loading rate determined the system’s capacity(the shovel was not able to keep up with the sizer station), also that production time lost during the relocation of the loader limited the benefits of the slewing facility. In addition, the company noted that the hopper target area and accessibility was of greater benefit than its capacity. Losses of production incurred when repositioning the conveyor was a majorconstraint, with continuity of operation more important than system capacity. Although a consideration, the time taken to lift and reposition the hopper support did not impact the production significantly. Downtime incurred with a conveyor system that was over 20 years old “emphasised the need for total system availability”.
The company compared the pros and cons of fully mobile and semi-mobile systems. Fully mobile systems are only suitable for consistent overburden orebodies, and the operating position is obviously quite inflexible. Any maintenance or breakdown entails total system shutdown with the ideal being a scheduled system shutdown of one shift every two weeks. But moving the sizer takes up to only around one hour per day and moving the belt takes about 3 days. For semi-mobile, the operating position is fairly flexible making it suitable for ore bodies requiring selective mining and blending. A system shutdown is only required for sizer or belt maintenance with a scheduled system shutdown of 20 hours per week. But a scheduled relocation of the sizer takes 3 to 7 days.
MMD concludes: “The factors dictating the most appropriate choice depend entirely on prevailing conditions and even then the answer is site specific, and as always a compromise between cost and the required rate of production. Fully mobile IPCC sizer systems are limited by the size of the loader which means that the only way to increase production currently is to add more systems.”
As MMD sizers are capable of handling far higher capacities than any current conventional loading tool currently available, their semi-mobile units offer the potential of being loaded by dozers or draglines, such as at the company’s customers in Colombia. MMD also designed its large semi mobile units in two self contained modules to facilitate relocation and so that these units can be used independently. Feeder modules without the sizer can also be loaded by dozers or draglines if the material is suitable for conveying without being broken.
Mineral sands and mobile mining
RCR is an Australian company with over 100 years of history, using in-house expertise to provide “innovative turnkey solutions that encompass all critical elements, from design and construction to maintenance.” The Mining Division of RCR, headed by Ian Gibbs, General Manager, is involved with mainly with the design and manufacture of materials handling and process equipment for the mining industry. In 2010 and 2011, RCR developed two significant mobile mining plants for the Australian mineral sands industry, supplied to Iluka Resources’ zircon. Both plants were developed to meet an increasing need for highly mobile and relocatable modular plant. These plants were designed and manufactured from concept to commissioning in two 12 month periods, and according to RCR have been both outstanding successes for Iluka. The group argues that a standardised approach has held back innovation and development in many Australian mining applications. In certain circumstances where an EPCM group does not understand or have expertise in IPCC, this may preclude its use even though the deposit may be perfectly suited to IPCC implementation of IPCC.
Other excuses cited include “we don’t have the time to plan the move”, yet haul roads are planned and extensively maintained for 30 years or more. Or the statement may be made that “our mine planners only have data on conventional mining” therefore IPCC is distrusted; or that the company says they have “limited capacity or operation time to perform regular maintenance” even though there is a dedicated workshop with around the clock maintenance personnel to support the trucking fleet.
RCR used computer-aided engineering techniques along with mathematical analysis of machine aspects for optimisation; as well as Finite Element Analysis of combined machine and structural components. The use of 3D design drafting assisted accurate estimation from the concept stage forward, but there was still a high financial and commercial risk due to the very short delivery schedule. The Australian mineral sands mining groups are by nature progressive and adaptive to allow them to maximise mining production in ever-changing and extensive surface ore bodies, as well as minimising environmental impact and cost. Traditionally mineral sands miners have used large fleets of scrapers in dry operations.
Iluka had worked closely with RCR previously, so the next phase was a progression. The NMB deposit in Victoria would allow the plant to be relocated every 7-10 days in a deposit about 200 m wide and 11 km long. The plants had to be highly mobile and self-propelled. RCR had already considered track mounted plants in other applications and had developed a basic understanding of the challenges and the potential applications. The first plant was required to be operational within 12 months, with the second plant requested for the JAA project in South Australia whilst RCR was completing the first and was required in an even shorter time frame.
In both cases the projects were completed on the principles of fixed lump sum pricing requiring very careful and controlled project management, and a well defined concept. The concepts originally prepared for both plants resembled the final product. RCR believes that this understated the underlying innovation and the complexity of the solutions which were achieved.
The first modular design involved the use of a known process, with apron feeder, scrubber and trommel. The design is based on relocations every seven days but now moves less due to ore body changes. Each module is self propelled and joystick-controlled. Module 1 weighs 480 t, has a dozer trap with maximum oversize of 1,200 mm, and apron feeder 30 m long and 2 m wide at 18 degrees; and a vibrating grizzly to reject > 300 lumps; an O/S transfer conveyor; high rise conveyor, transformer and 350 hp power Unit for reloactions. Module 2 is 400 t, has an autogenous scrubber; oversize conveyor, and a 14 /12, 355 kW Warman pump. Module 3 is also 400 t and has a rotating trommel screening producing a < 2.5 mm slurry feed to the Plant, two 14 /12 Warmans and an oversize conveyor. The second design for South Australia is a single unit but is self propelled and was based on relocations every 30 days, with the module both self-propelled and joystick controlled. The anticipated throughout was 1,500 t/h of ROM feed but is now running at close to 1,800 t/h. The machine has a 30 m x 2.5 m apron feeder angled at 18°, a dozer trap with maximum oversize of 1,200 mm; a vibrating grizzly for < 300 mm feed to a 4 m to 9 m scrubber/trommel. It also has two 14/12 400 kW Warman pumps 400Kw for < 10 mm slurry feed, an 850 hp hydraulic power unit. The plant has eight tracks and can rotate in a 50 m radius and sits on the structure whilst in operation while the tracks are elevated. The configuration allows for multiple directional loading conditions with three axis rotational degrees of freedom.
Lowering the resistance threshold
Doug Turnbull, Sandvik Principal Mining Engineer began by pointing out that history has seen many IPCC failures, with many pretending to know all about IPCC but with few having real and extensive experience. Companies have no trust in IPCC, and many do not believe it is a viable solution; with an underlying reluctance to get rid of their trucks. A lack of IPCC teaching as part of mining engineering courses at universities is also an issue, as is a lack of commercially available IPCC scheduling software. At the same time, some companies are embracing and making IPCC work far more competently than others – which comes down to the right planning and understanding of the risks. Crucially IPCC needs a mine plan that functions for the equipment selected – 7 out of the 10 failures due to ill-informed mine plans.
Turnbull summarised the key points that need to addressed to have the best chance of success – namely that IPCC requires firm planning, not flexibility; that operating hours must be achieved; that the chosen crusher and conveyor planned relocations are realistic; and that the material parameters, especially those for waste, which are often ignored, are well known. The planned throughputs must be achieved where possible. He also dispelled some myths about IPCC – namely that systems are too prone to damage from blasting and trucks colliding with conveyors. While these are risks, in reality, accurate blasting can be conducted relatively close to conveyors; and while the latter point is also a factor, the IPCC system will mean a smaller truck fleet.
There is no doubt that the electricity requirements for IPCC are high (though regeneration of power for downslope conveying is an option) and that the key mine planning criteria must be understood. The mentioned lack for specific IPCC software for scheduling does not help, but grade control can still be achieved.
When a decision is made to proceed with IPCC, there are several key planning steps – not least finalising the crusher location. Turnbull described the criteria to best locate the crusher area for a semi-mobile or semi-fixed crusher, including low preparation demand regarding the crusher box and conveyor routes; and making it accessible before actual mining operations start. The crusher area should also be protected from groundwater and surface water; with interference in the crusher area from truck and shovel operations minimised. Safety as elsewhere is paramount in terms of geotechnical and operational issues. The haulage distances should be at a minimum between the shovel and crusher, in terms of the bulk material allocation flow. Any relocations should be well prepared for in advance.
A whole different set of parameters come into the dump/spreader location. These should all be ex-pit or in a backfill area, with low downtimes due to dump conveyor shifting – with less than 12 shifts per year preferable. There should be a large dump volume, with a long dump conveyor length; and large spreader boom/bridge to suit the geotechnical parameters and maximum achievable width. There should be a maximum deep cast height; with preparation on higher layers during dumping operations on lower levels. Spreader areas also often have significant dust emissions issues that need to be addressed.
Finally, in defining the conveyor route, it is important to maximise the dump conveyor length and ramp conveyor gradient, and the bench conveyor length if a fully mobile system. Ramp conveyor length, the number of transfer stations and preparation volumes should all be minimised. For fully mobile systems and the example of the Sandvik PF300, the system needs “superb maneuverability”, support under the hopper, an independent bridge connection, compact design, and high stability. For material with clay, minimising obstacles loading is important to avoid sticking – such as no grizzly bars, no rock boxes, no spoons or lobster back chutes, with maximum vertical discharge where possible, and flexible curtains with no sticking points.
For conveyor reloaction, track shifting using a pipe layer equippped with track shifting head was referred to as the best available option in most cases, with the conveyor connected to rails; and the lifting achieved with lateral movement while travelling along the conveyor – several passes of about one metre will be needed to achieve the final position but it can be fast, with typically a conveyor length of 2 km having the ability to bemoved 80 m in only one 12 hour shift.
Turnbull closed by making an analogue between IPCC and longwall mining. It was only in the 1970s that longwall methods saw a lot of inertia as an alternative mining method for similar reasons – there was concern due to the different demands on mine planning with regard to strata control and ventilation design, as well as the relocation process being relatively unknown and the capex upfront being high, the opex being unknown, perception of inflexibility, examples of early failures and resistnace due to resulting manpower reduction levels.
But like IPCC the reasons for introduction were clear – more coal could be extracted at lower cost, yes there are less personnel but these have a higher skill base, the simplicity of layouts allows for predictable outcomes, there are no tyre issues, the method is truly continuous mining, there are no diesel usage issues, and more resource is extracted leaving less support/pillars behind. Crucially, there is a high degree of automation with increased safety.
Once longwall introduction commenced, it gathered momentum and hasn’t looked back. The hard work on IPCC has been done by the pioneering operations, and there is no reason it shouldn’t also achieve its potential. Sandvik has a number of projects underway currently. Two cited were the Antucoya copper project in Chile and the Hongsa coal project in Laos. At Antucoya, Sandvik is delivering in 2013 the design, supply and installation of a crushing and conveying system, including primary in-pit crushers, overland conveyors, a secondary and tertiary crushing and screening plant, auxiliary equipment and electrical instrumentation and control systems.
At Hongsa, Sandvik is delivering the design and supply of continuous mining equipment for overburden removal and coal handling, with MMD having the contract at the same mine for nine semi-mobile sizing units. The Sandvik portion includes 15 PC200 conveyors, two slewing stackers (PS200-1800/38), three bridgetype reclaimers (PR300-1400/52), two secondary crushers, five PC300 relocatable mine conveyors, two PC300 relocatable mine conveyors, one spreader PA200-2600/52+50 with tripper car, and two PT300 transport crawlers.
In a second presentation, Thomas Jabs of Sandvik Mining Systems pointed out that 34% of the global seaborne iron ore is loaded with Sandvik ship loaders; illustrating the company’s across the board experience in bulk handling. He identified three main sources for misunderstandings/disappointments in IPCC projects – namely available operation time in continuous and semi continuous mining operations; calculated and expected tonnage per hour; and where a system is implemented, but not operated as required. In terms of available operation time, Jabs proposed a maximum operating time per year in continuous or semi continuous mining operations as between 5,000 and 5,800 hours, not more, as numbers above 6,000 hours will lead to problems in the calculated yearly output.
He also emphasised that “continuous mining means continuation of plans.” The requirements towards mine planning and production planning are more complex. Any big differences in ore grades or constantly changing layers of coal/overburden/interburden and the required change of conveying routes need to be planned upfront and the geology needs to be known as exactly as possible. Maintenance also needs to be planned differently, with shutdowns of individual lines required. The type of maintenance is different – involving a series of tasks including crusher maintenance in the crushing chamber, belting, splicing, capital and insurance spares as well as regular chute maintenance.
Sandvik also offers a co-operation opportunity for IPCC in the form of a Build-Operate-Transfer (BOT) model. Jabs stated: “IPCC is slow in market acceptance due to technical and commercial risks that mining customers are reluctant to take. A BOT model could help to overcome the reluctance and speed-up the change in technology in mining.” Sandvik Mining Systems have teamed up with “a major multinational” that has the finance power and the long standing track record in the mining industry. Sandvik’s partner and Sandvik would enter into a BOT contract with the mining customer, where Sandvik will build the IPCC plant and operate the plant for a defined period during which Sandvik’s partner owns the plant. After this period (2-3 years) of operation and proof of technical and commercial parameters, the mining customer takes over the plant at agreed conditions. During the initial operating time, the customer pays in the form of fixed costs and a cost/tonne basis. Sandvik’s partner finances and commercially administrates the BOT contract, with the contract closing at the time of transfer and purchase of the plant by the mining customer. Aftermarket/service contracts after transfer are optional.
The advantages are significantly reduced capex for the mine owner and full leverage of the expertise of the OEM. Sandvik is on site for at least this period to train customer employees in IPCC and all initial performance burden is with the BOT partners to prove the system is working. The customer is not “left alone” with the system, but integrated in ramp up, training and operation.
IPCC practicality and decision making
Two presenters from FLSmidth’s IPCC team – Lynn Peterson, Product Sales Manager and Glenn Davis, Global Sales Manager – discussed the decision making process and determining factors considered in evaluating the economic viability of IPCC systems, and presented IPCC alternatives to a conventional truck and shovel solution, including comparison of the overall costs of truck and shovel to alternative IPCC solutions based on capex, opex and cash flow for a case study coal mine project. In 2012, FLSmidth constructed what it believes to be the world’s largest single semi-mobile IPCC system for Goldcorp’s Penasquito mine in Mexico, capable of 12,500 t/h and employing an ABON 16/350 CCTD low speed sizer as well as a 3.15 m-wide D11 low angle apron feeder. The company is also completing construction of a complete IPCC system at PT Adaro’s Tutupan operation in Indonesia, which has been previously covered in IM.
The presenters stated that: “Although the goals and practicality of IPCC are intuitively evident, there is a general level of uncertainty concerning the magnitude of benefits derived, and the parameters determining feasibility.” The primary economic benefits were cited as significantly reduced operation costs, primarily through a reduced truck fleet – reduced fuel, tyres, labour, maintenance and road maintenance – with only the weight of material and belt being moved. There is an associated reduced replacement capital requirement, and these two combined result in reduced yearly cash flow. There are also lower incremental costs in material transport distances and as most of the cost of the conveyor is in the head and tail sections; adding distance in midsection is relatively inexpensive compared to adding more trucks. As previously mentioned, it is also easier to recover energy through co-generation.
The secondary quantitative benefits include less dust and reduced water requirement for dust control; reduced CO2 emissions using reduced carbon fuels to make electricity; less noise; and reduced logistics support issues associated with trucks, namely in terms of training, parts, labour availability and fuel delivery. There is a reduced weather impact on operations as well, with IPCC being able to run where trucks cannot.
Disadvantages of IPCC of course include a higher initial capital with most of the capital investment requirement required upfront – truck and shovel can be incremental as production is ramped up. Not often referred to is the fact that IPCC requires the additional cost of material sizing before transport. There is also the limited flexibility to changes in mining plan and allocation of labour/equipment resources; while it can be difficult for IPCC to adapt to an existing operation and equipment inventory resulting in a less than optimal system and reduced benefits if an IPCC “retrofit” is attempted. It also involves a serial equipment interface with few backup options, where even individual component downtime can affect the whole system and operation.
The decision process is effectively an economic tradeoff between IPCC’s lower operating costs versus a truck fleet’s lower initial capital and flexibility, taking into account the value of the mentioned secondary qualitative benefits, and the respective risk involved.
Factors favoring truck and shovel include any limited availability of capital, if there is a low flexibility in the mining plan to accommodate IPCC, and if there is a poor match of existing equipment inventory and facilities to IPCC requirements. Added to this are where there is inexpensive labour, shorter haul distances, lower production rates and a short mine life – all of which tend to count against IPCC. But in its favour are longer material transport distances, higher production rates, higher lifts, where there are high fuel costs, where there is access to inexpensive electricity, and where there is expensive labour.
Semi-mobile IPCC offers a degree of mobility – with relocation every 3-5 years. Having a fabricated steel chassis, it has minimal foundations, with civil works limited to a retaining wall and truck aprons. Relocation is typically by transport crawler. Fully mobile systems are generally direct shovel-fed, with rock fed into a mobile overland hopper that rides on a shiftable face conveyor. Self propulsion offers complete mobility making them better suited to strip mining of stratified deposits.
FLSmidth’s “outside the box” solutions include its Dual Truck Mobile Sizer – DTMS, which uses a standard semi -mobile type station with hydraulic hoppers, but eliminates all earth works and retaining walls, making it effectively a mixture of semi mobile and fully mobile IPCC. It also works with the same shiftable conveyor system as a fully mobile system and offerscomplete mobility as needed. It can be self propelled or use a transport crawler.
Another design from FLSmith is the Continuous Loader option, based on equipment it acquired from Holland Company. This design consists of vertical cutting blade and horizontal blade options, with more than 80 units currently sold. This is currently being re-designed for bidirectional use and self propulsion. Using a Continuous Loader with mobile bridge conveyor with horizontal cutting blade feeding trucks or mobile overland Hoppers / face conveyors can achieve 12,000 t/h capacities in the right type of softer deposit such as alluvial-type material.
The smaller FLS Mobile Dozer Trap, also developed from Holland Company solutions, offers capacities up to 4,000 t/h. It is fed by four dozers and feeds a mobile overland hopper. It is relocated via dozer but like the Continuous Loader has a much reduced capex and opex from a more complex
In terms of key components offering different IPCC design scenarios, FLSmidth has a wide range of options. Its mobile mining conveyor is a self-propelled bridge type offering where a mobile reclaim hopper receives material. This can be 100 m to 1,000 m plus in length and can be teamed with a fully mobile IPCC rig to reduce shifting frequency. It can also operate in a linear or radial manner. The group also has a unique range of cusher and feeder options including gyratory, cone, jaw, hammer mill, HPGR, sizers, feeder breakers and roller screens as well as apron, belt, chain, roller and vibratory screens.
For waste stacking, the mobile boom spreader is a crawler mounted machine with a link conveyor to provide flexibility. Operating in conjunction with a rail or crawler-mounted tripper car riding on a shiftable waste conveyor, the system can radial or linear stack waste – with both advance stack (downcast) and retreat stack (backcast) configurations possible.
Portable conveyor options include grasshopper style or bridge style conveyors, which can be rubber flotation tyre mounted or crawler mounted and can be used to link in-pit conveyors in transitional benching areas. The mobile stacking conveyor (MSC) is a bridge type conveyor with tripper car to discharge material, with independent crawlers on each hinged frame section, and each frame hydraulically cross leveled. It can be combined with the mobile boom spreader with the MSC built on the starting ramp at the desired pile height; and advance stacking waste into a radial arc (sweep) or retreat stacking to increase pile height. This can be used in conjunction with both extendable and shiftable conveyors on a waste dump.
Putting all the pieces together
ThyssenKrupp’s Leif Erik Berndt pointed out that rising volumes, lifts and haul distances are working in favour of IPCC systems and conveyors but that these systems require long term planning to deploy effectively. In the fully mobile arena, the group delivered a fully mobile system at the YiminHe mine in China, capable of 3,500 t/h coal and designed for 9 Mt/y, but with production of 11 Mt achieved in 2011.
ThyssenKrupp has a unique IPCC heritage, having put in arguably the first mobile IPCC system at Nordcement in Hanover in 1956 leading up to its most recently commissioned fully mobile systems at Baiyinhua in China. Four fully mobile crushing systems have been delivered, with three of the four systems being used to remove coal overburden, each having a design capacity of 6,900 t/h. One 3,500 t/h system will be used for coal processing. Again the point was made that fully mobile crushing plants are the least weather dependent, with semi-continuous systems continuing to operate only when loading units are on the same level.
The company also put in Indonesia’s first large semi mobile IPCC systems for overburden at Freeport McMoRan’s Grasberg mine, installed in 1999. The group pointed out that in competent material, natural pockets are enough for a semi-mobile installation, being “strategically located in the pit to reduce the haul distance of dump trucks”, with the crushing plant matched to truck size.ThyssenKrupp has a unique IPCC heritage, having put in arguably the first mobile IPCC system at Nordcement in Hanover in 1956 leading up to its most recently commissioned fully mobile systems at Baiyinhua in China. Four fully mobile crushing systems have been delivered, with three of the four systems being used to remove coal overburden, each having a design capacity of 6,900 t/h. One 3,500 t/h system will be used for coal processing. Again the point was made that fully mobile crushing plants are the least weather dependent, with semi-continuous systems continuing to operate only when loading units are on the same level.
In technology development, ThyssenKrupp has been working with indurad on implementation of its iDRR (Indurad Dual Range Radar) at transfer points. From a crusher point of view, ThyssenKrupp has a complete range but has had success in the use of double roll crushers in IPCC projects, which it believes to have the highest availability by use of floating rollers; and offering the best fit for overburden, accepting large lumps and varying feed characteristics. The double roll crusher has easy access for tooth replacement and maintenance purposes.
The presentation rounded off with a series of reference summaries, such as the installation at Albian Sands’ Muskeg oil sands mine in Northern Alberta, with a semi-mobile 14,800 t/h double roll crusher of type WB 2600 x 3400, with an 18.5 m apron feeder and D11 chain. Spreader references from ThyssenKrupp exceed 550, up to a capacity of 27,500 m3/h at the RWE Hambach mine. Common sizes of boom lengths are 50-60 m.
Getting the right scope
Takraf’s Rico Neumann, Chief Engineer Mine Planning, began by focusing on the planning, calculation, re-planning and recalculation of IPCC systems, all of which it offers in short term studies. These home in on the application of mining, crushing, conveying, dumping and stockpile equipment in operating mines or greenfield projects. Studies can incorporate mine planning, project planning, operating models, capital cost and operational cost calculation, as well as trade-offs between different operational systems to find pro and cons and overall cost development. These studies can form the basis of mining discussions in prefeasibility and feasibility projects.
Most recently, an IPCC trade-off study for waste and ore was completed for the Miheevskij mine in Russia; and an order of magnitude IPCC study was done for Rio Tinto Kennecott Utah Copper, looking at crusher/conveyor options and truck traffic at the pit wall; as well as planning of crusher relocation and external spreader waste dumps. A further IPCC waste study looked at dump design in a mountain area for a mine in Vietnam, while an IPCC equipment design study in Colombia was completed.
More than 20 semi-mobile crushing plants from Takraf delivered since 1995 are working in Chile, Mexico, Brazil, the UK, Indonesia and Russia. They are equipped with gyratory, sizer or jaw crushers and have crushing plant design capacities ranging from 3,600 t/h to 8,800 t/h. In terms of crushing plant selection (whether fully or semi mobile or fixed), the company cited space available for benches/ramps and equipment; safety aspects of blasting near equipment; interferences of haul/access roads with conveyors; the shovel operating scheme; and whether there is ROM ore blending in the pit. A fixed crusher has a low investment cost and is preferable at the final pit rim – making for a “clean”, conveyor free pit.
Semi-mobile reduces reduced truck haulage, is independent from the working bench advance (blasting/loading/hauling), and relocation can occur with pit development. Fully mobile systems see the complete elimination of truck haulage but allow for a maximum of three-bench operation with one conveyor. Neumann also compared the construction/bench height; space requirement (area); and relocation issues versus the deployment of an internal or external surge bin; and the choice of a ROM apron feeder. Structual designs for semi-mobile crusher plants are based on results of structural calculations and finite element analysis with static and dynamic loads, with operational and relocation, even earthquakes.
Moving onto conveyor systems, Takraf summarised its current thoughts on available parameters. State of the art in-pit overland dumping/stockpiling conveyor solutions delivered by the company include Radomiro Sulfurus in Chile where an installation handles 7,700 t/h, is 8 km long, with a 240 m lift, and has three horizontal, and 11 vertical curves.
Helping to reduce downtime caused by conveyor shifting, extension and relocation can include the use of crawler mounted conveyor head stations and belt storages. Conveyor distribution points at transfers from Takraf have included crawler mounted conveyor head stations with shuttle heads; and fixed conveyor head stations with shuttle heads. The company has also installed an 18° pit ramp conveyor as part of an IPCC system at the Wostotschnij mine in Kazakhstan.
Waste dump design alternatives include a dump conveyor with mobile head station, no tripper car, a long spreader connecting bridge with support crawler, and additional Mobile Transfer Conveyors (MTCs); a shiftable dump conveyor with tripper car on rails or crawlers, single boom stacker or spreader with connecting bridge; and mobile conveying stacking bridges for small dumping heights.
Installations include Toquepala in Peru, with a design capacity of 5,250 m³/h, low dump height up to 100 m and high dump height of 15 m. This system has a connecting bridge of 95 m, discharge boom of 50 m, and conveyor bridge on Crawlers of 60/150 m. An example of mobile conveyor bridges is at Gaby in Chile, with seven segments supported by eight double crawler assemblies. It has a total length c/c pulley of about 485 m, slewable discharge conveyor up to 45° to each side and a maximumcapacity of 9,300 t/h.
Recent semi mobile orders include Radomiro Tomic, Chile (7,700 t/h for copper ore, 2010); Bloom Lake, Canada (3,900 t/h for iron ore, 2009) Roy Hill, Australia (5,600 t/h for iron ore, 2012 – three units handling primary of product of 350 mm and secondary product of 100 mm). Finally at Lomas Bayas in Chile this year, the company has delivered a semi mobile system for 3,100 t/h copper ore incorporating a 54-75 gyratory and 48 m feeder/discharge conveyor. The crushing plant only has bolted field connections with no field welding.
The company supplied the waste conveying and stacking system to Goldcorp Penasquito (with FLSmdith delivering the rest of the project) including a shiftable dump conveyor of 1,000 m, head conveyor of 2,000 m, and overland conveyors of 3,500 m downhill and 1,800 m uphill.
The Rio Tinto Clermont fully mobile system was delivered in 2009 and has a crushing capacity of 12,000 t/h handling overburden, mainly basalt and sandstone, using a twin shaft 1600 sizer. This rig remains in its first phase of operation, in a stationary mode with truck dump. The new Takraf Mobile Crushing System (TMCS) fully mobile IPCC type system with options for discharge boom and/or belt wagon or mobile conveying bridge only involves 85% of the investment cost of the Clermont type machine, plus has a different operational scheme and mining sequence with less downtime. The complete mining of bench ends is achieved behind the conveyor head and tail station.
Finally, the company reported on the 8,500 t/h IPCC system delivered to Wostotschnij in Kazakhstan which handles overburden, mainly siltstone, claystone and sandstone and uses double roll crushers. The system consists of two semi mobile crushing plants of 4,250 t/h along with a pit ramp conveyor, overland conveyor, dump ramp conveyor and shiftable dump conveyor as well as tripper car and spreader.
Combining components
Joy Global’s presentation, given by Stuart Miller, Director Operations – Joy Global Indonesia and Bernard Guillemin, Business Development Manager, IPCC began with another look at the Indonesian mining environment. They pointed out that Indonesia’s coal quality is getting lower and at the same time energy adjusted costs of Indonesia’s most emerging coal production areas will be among the highest in the seaborne market going forward. This combined with increased operating costs, divergence of diesel costs and coal FOB pricing, tyre shortage for haul trucks, new stricter environmental regulations and other factors, all combine to make a strong argument for the implementation of IPCC in the country – and this is in addition that the mine and deposit types are mostly also well suited.
The core of the Joy Global IPCC turnkey system is formed of an integration of JoyGlobal’s own components, added through a series of acquisitions – Stamler in 2006 adding a crushing option, Continental Conveyor in 2008 adding a series of conveyor designs including high angle options, and in 2011 the Le Tourneau acquisition adding the world’s largest wheel loaders with Switched Reluctance (SR) technology. This added a new loading tool to the company’s already leading rope shovel range, including the recently launched 2650CX hybrid shovel and the new class leader, the 4800XPC.
The company described a case study from the Wyodak coal mine in the Gillette Energy Complex, Wyoming, which feeds a mine mouth power station generating 800 MW. The mine’s production reached approximately 5.7 Mt in 2011, with overburden removed by conventional truck/shovel operations, with average stripping ratios of 2.6 to 1. It is a multi-seam operation with variable coal quality and blending is required to meet end user requirements, carried out at the CPP. Two Stamler feeder breakers are used – one track mounted and one skid mounted; along with a 2,150 t/h overland conveyor powered by twin 500 hp VD DC motors plus a 2,150 t/h feeder conveyor and a High Angle Conveyor (HAC) inclined at 60° for a 50m lift, powered by a 300 hp DC motor. There are also two 4,500 t coal silos located at the CPP. Computerised communication, command and control system enables single operator control. According to Joy, the system has delivered 93% overall availability and has been in operation since 1994. Wyodak has seen both a reduction in carbon footprint and operating cost per tonne. A number of other mines in the Powder River Basin have taken Wyodak’s lead and are looking at IPCC options.
JoyGlobal’s current turnkey fully mobile IPCC system is focussed on overburden removal projects and consists of a Mobile Mining Crusher (4170C) capable of 12,000 short tons per hour, which is matched to the production of the 4100XPC. In its own product range, Joy has overland, High Angle Conveyor (HAC) and spreader conveyors. The group sees the fact that all of its own system components are linked will help to optimise productivity on a continuous basis. The system also has on-board analysis; continuous data collection of cycle times and production rates; and the Joy Global IPCC Remote Monitoring System which provides synchronised maintenance schedules for the entire system. This enables remote access to multiple users, supports comprehensive analysis and reporting, uses fault logs and histogram reporting and interactive flowcharts, and includes electronic manuals, schematics and parts books Finally, JoyGlobal Mine Planning Tools offer “4D modelling” capability of 3D Topography with 3D Equipment over time, allowing mine planners more flexibility to integrate movement of IPCC System with rest of the overall mine plan.
Joy also provides customers with detailed evaluation with a side-by-side Total Cost of Ownership (TCO) sensitivity or “what if” analysis, which allows the user to quickly understand the quantified reasoning with respect to a comparative analysis and the resulting optimal equipment selection.
The company states: “Capital acquisition that disregards equipment reliability and performance can pose a significant overall financial risk regarding the viability of a given mining application. Total Cost of Ownership analysis is advantageous over using just capital justification because product price is one of the most unpredictable cash flow components. Conventional Net Present Value based analysis requires a full system or complete mine-site study in order to understand the revenue associated with a particular mining application.” IM
