Modern Quarrying Q2 2019

QUARTER 2 – 2019

FULL PROCESS-FOCUSED SOLUTION PAYS DIVIDENDS

CONTENTS Having operated a downtime-ridden plant beleaguered by excessive breakdowns, extreme maintenance glitches and low throughput setbacks, the quest to increase production efficiencies and reduce operating costs saw CNCCrushers purchase a full process-focused solution fromWeir Minerals.

QUARTER 2 – 2019

ON THE COVER

CRUSHING

WHEEL LOADERS

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ACHIEVING SCREENING EFFICIENCY PAGE 26

THE PRACTICAL PROBLEMS OF WORKINGWOMEN INMEN’S CLOTHING PAGE 36

AROUND THE INDUSTRY 04 Aspasa protects surface miners’ rights 05 Q4 2018 ACI shows reality of sector challenges 06 Calling for new beginnings SUPPLY CHAIN 37 Blasting solutions that take operations into digital age 38 FLSmidth opens high-tech facility to manufacture 38 screen media 39 Savings for Weir Minerals’ customers in Africa

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REDEFINING SERVICE WITH UPTIME INMIND Equipment health is a very important parameter in overall productivity and, consequently, the bottom line of every quarry. It is for this reason that a discussion on the future of service should be of interest to the industry.

LEADING THEWAY TOWARDS ZERO HARM At a time when the South African mining sector is battling high numbers of fatalities at operations, members of surface mining industry association, Aspasa, have reported no fatalities across their operations for the third year running.

CIRCULATION Karen Smith PUBLISHER Karen Grant

EDITOR Munesu Shoko quarrying@crown.co.za ADVERTISING Bennie Venter benniev@crown.co.za DESIGN Ano Shumba

DEPUTY PUBLISHER Wilhelm du Plessis

PRINTED BY: Tandym Print

PUBLISHED QUARTERLY BY: Crown Publications P O Box 140 Bedfordview, 2008 Tel: +27 11 622 4770 Fax: +27 11 615 6108 www.crown.co.za

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TOTAL CIRCULATION 2 465

The views expressed in this publication are not necessarily those of the editor or the publisher.

TURNING THE HEALTH AND SAFETY CORNER

I remember having a conversation with Afrimat CEO Andries van Heerden back in 2016 on matters relating to health and safety in the quarrying industry. He narrated a rather funny story that reflected how the local quarrying fraternity had turned the corner in terms of health and safety at operations. He recalled how he had joined a “rough industry” some 20 years back, and at the time one of the quarries used small 5-tonne trucks to haul run of mine material from the pit to the processing plants! Interestingly, he also told me how they would park these trucks on an incline for hill starting purposes. Big rocks would be placed in front of the wheels because these trucks didn’t even have parking brakes. The driver would jump in while the assistant would pull away the rocks to let the truck roll before it started. Today, story like this sounds unbelievable – that’s because the

that Aspasa’s ISHE Audits have ushered in new health and safety standards at member operations. Nico Pienaar has also shown his passion for an industry that many still don’t really appreciate for its value to society. Together with his team at Aspasa, they have put in the hard yards to make this industry what it is today. Kudos to quarry operators as well for the high safety standards we see at operations today. Many have well understood that attention to health and safety is not just about being socially responsible. It also makes good business sense and should be regarded as important as the achievement of any other key business objectives. Of course, working out what modern health and safety law means for your business can be quite a headache. But that shouldn’t put you off. Yes, on the face of it there do seem to be a lot of regulations, but the underlying principles are really quite straightforward. Addressing health and safety should not be viewed as a regulatory burden. Benefits of a well-defined health and safety structure are wide ranging, and can include, among others, reduced costs; reduced risks; lower employee absence and turnover rates; fewer accidents; lower threat of legal action; improved standing among suppliers and partners; better reputation for corporate responsibility among investors, customers and communities; as well as increased productivity, because employees are healthier, happier and better motivated.

industry has reformed to world-class standards. Obviously the regulator has played some part in tightening the screws, but much of the credit should go to the industry itself for its commitment to a new health and safety era. As you will see in the Safety Feature of this edition of Modern Quarrying , at a time when the South African mining sector is battling high numbers of fatalities at operations, members of surface mining industry association, Aspasa, have reported no fatalities across their operations for the third year running. Central to this feat is the adoption of an advanced health and safety regime that has ensured that member operations are at the forefront of the industry’s journey towards Zero Harm by 2020. When talking about these achievements, it would be fair to shine the spotlight on industry association, Aspasa. Many will agree

COMMENT

Munesu Shoko – Editor quarrying@crown.co.za

@MunesuShoko

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INDUSTRY NEWS

Aspasa protects surface miners’ rights

With profits under pressure as a result of continuously onerous compliance issues and other challenges, it is increasingly beneficial to become a member of Aspasa, a surface mining association that has the best interests of its members and the indus- try at heart. Aspasa director, Nico Pienaar says there are 12 overarching services within Aspasa that the association wants to highlight. “Technological advances are at the forefront of innovation, especially in transport with Trackless Mobile Machinery (TMM), Proximity Detection Systems (PDS) and regulations relating to road transport in general. New members will be brought up to speed on trackless mobile machines regarding risk assessment, the implementation of effective controls, traffic management and colli- sion avoidance technology requirements,” says Pienaar. “Proper risk assessments and Traffic Management Plans (which should actually be already in place) outweigh the cost of Section 54 stoppage,” says Pienaar, adding that fitting PDS systems are not yet fully functional, but several systems are being tested by Aspasa and suppliers to stay up to date with latest technology. “Secondly, Aspasa helps members technically, in terms of the quality of the aggre- gate mined and the final product sold, as well as information related to the production process. In essence, a mine should have a quality management programme in place which can be audited regularly. Aspasa has developed such a programme with links to relevant methods, standards and specifications,” adds Pienaar. Checklists show the member how to implement the programme, especially proce- dures for sampling and testing and then the reporting and communicating of a quality product delivered to your customer. “Engineering is another service covered by Aspasa which should be of enormous importance to members as it gives advice on how changes to the Mine Health and Safety Act of 1996 impacts on engineering research and development. Aspasa has taken up the development of engineering career paths in surface mines and has a committee that deals with it.

Nico Pienaar, director of Aspasa.

“Of vital importance to members and therefore to the industry as a whole is Aspasa’s liaison with government. An allied service is to ensure its members are legally compliant. The association’s liaison with government is evident in the stakeholders’ submission to the Mining Occupational Health & Safety Research Programme. . l

Calling for urgent government intervention to save the construction industry

matter remains unresolved. “The decline has reached a very concerning level, so much that it is no longer a sectoral prob- lem but a national crisis. We appeal to the government to open up to the indus- try and urgently find concomitant solu- tions to save it from a total collapse”. He, however, acknowledges that there are other factors instrumental to the demise of the industry. These include a sluggish economy, reduction in ‘actual’ infrastructure spending by the govern- ment, as well as illegal and often violent work-stoppages at construction sites by various illegal forums. The adverse impact of these company closures are severe, he notes. “The short-term effect is that direct employ- ees of these collapsed companies lose their jobs. When you consider that the construction industry employs more than 11% of the workforce in South Africa, the negative impact on the economy as a whole is dire. There is also a knock-on effect across the industry because

Master Builders South Africa is calling for urgent government intervention to prevent further destruction of the construction industry in the country. The call follows Group Five’s filing for bank- ruptcy protection in March this year, the fifth major construction company to do so in less than a year. Roy Mnisi, executive director of Master Builders has expressed deep concern on the matter. “This is the fifth large firm to succumb in less than a year. In 2018 alone, NMC Construction went into vol- untary liquidation while Basil Read, Esor Construction and Liviero Group applied for business rescue. We still have many other small-medium sized firms facing financial difficulties and yet, there has not been any government-industry engagement to develop a plan to halt the trend.” According to Mnisi, the industry has continually engaged government on the adverse impact of late/non-payment of contractors for work completed but the

Roy Mnisi, executive director of Master Builders South Africa.

subcontractors, suppliers and service providers are equally affected.”

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Q4 2018 ACI shows reality of sector challenges Afrimat, the JSE-listed open pit mining company provid- ing industrial minerals, bulk commodities and construc- tion materials, has released the findings of the Afrimat Construction Index (ACI) for the fourth quarter (Q4) of 2018. The ACI is a composite index of the level of activity within the building and construction sectors, compiled by renowned economist, Dr Roelof Botha, on behalf of Afrimat. According to Botha, the recovery in Q4 2018 was not suf- ficient to lift the index to a higher level than a year earlier. The average value of the index in 2018 was 4,7% lower than in 2017 and it is clear that the South African construction sector has been under-performing since the end of the recession in 2009. “When compared to the same quarter a year ago, five of the eight constituent indicators remained in the red, with substantial declines in the value of building plans passed and completed, as well as the volume of building materials produced,” he says. Botha points out that real GDP increased by 1,1% during Q4 2018 on a year-on-year basis, but the value added by the construction sector declined by the same margin during this period – a clear indication of the stressful conditions being experienced by the sector. “It is, however, encouraging to note that the index level has risen for the third consecutive quarter, following a below-par performance in 2017 and a fairly sharp dete- rioration in the first quarter of 2018. The index recorded a gain of 3,9% in the fourth quarter of 2018 and is now 14,4% higher than during the first quarter of 2018,” says Botha. “This reflects a continuation of a broad-based recovery

of the level of activity in the sector since the beginning of 2018, with five of the eight constituent indicators record- ing gains over the third quarter.” He indicates that the best performers during the fourth quarter of 2018 were salaries and wages in the sector, the value of hardware retail sales and building material sales. l

The recovery in the last quarter of 2018 was not sufficient to lift the index to a higher level than a year earlier.

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ICMM TO CREATE AN INTERNATIONAL STANDARD FOR TAILINGS DAMS

appropriately, consistently, and transparently. While the standard would become a member commit- ment, ICMM will encourage others to join us in advocating for it to be adopted more broadly,” says Tom Butler, CEO of ICMM. ICMM will engage with representa- tives from civil society, communities, industry, investors, and multilateral organisations, to determine the detailed scope of the review. The review will be carried out by a team of experts from diverse disciplines, led by an independent chair and is expected to be complete by the end of 2019. l

A global and transparent con- sequence-based tailings facility classification system with appropri- ate requirements for each level of classification A system for credible, independent reviews of tailings facilities Requirements for emergency plan- ning and preparedness “ICMM CEOs have committed to creating a step change for the indus- try in the safety of tailings facilities by developing a recognised interna- tional standard for member com- panies. The standard will be based on best practices to ensure that tailings facility risks are managed

The International Council on Mining & Metals (ICMM) has announced its governing Council of 27 member CEOs will establish an independent panel of experts to develop an international standard for tailings facilities for its member compa- nies. The standard will be informed by a review of current global best practices in the mining industry, and beyond. The standard is expected to create a step change for the industry in the safety and security of these facilities. The details of the standard will be defined through the review process but are expected to include:

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INDUSTRY NEWS

Calling for new beginnings

Despite the oversupply in the cement sector, AfriSam is now in a better position to cope with current market conditions after a period of right-sizing its business. Following Finance Minister Tito Mboweni’s first budget, economist Dr Azar Jammine has raised hopes for a “major recovery” in the South African economy, but warns it is unlikely to happen before 2021. Speaking at AfriSam’s 2019 National Budget Breakfast in Sandton recently, Dr Jammine told a diverse audience of more than 200 people from the construction sector that 2019 and 2020 would remain very difficult. Planned government investment in infrastructure, for instance, is expected to rise only 4%, spelling a continued slump for civil engineering. He says one of the key drivers of recovery would be restor- ing the tax-collecting capacity of the South African Revenue Services, which has fallen about R40-billion short of target in the last financial year. He also hopes that government expenditure will be made more effective if the challenges at the State-Owned Enterprises are addressed and the more- than -34% of the tax revenue being spent on the civil service is reduced significantly. Focusing on the state of the construction sector and its prospects, Industry Insight senior economist David Metelerkamp painted a sombre picture for most segments. The hard-hit civils sector will see some light from the 14% increase in planned government expenditure in transport and logistics infrastructure. Metelerkamp notes that this is off a low base from last year, moderating its likely impact. Water infrastructure will see an 8% increase in public spending, but investment in power facilities is only slightly raised due to the Medupi and Kusile projects approaching completion. The renewable energy sector will bring some relief to contractors, as its role in power generation could grow as these technologies show evidence of reducing the cost of generating electricity. The building industry looked better than civils, he said, especially the residential segment. This was mainly in demand for flats and townhouses, where square metres completed grew considerably in 2018. Demand for ‘luxury homes’ was down. The future held promise for large mixed- use develo pments, of which over 30 were on the table,

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CNC Crushers’ working relationship with Weir Minerals Africa started at Shaft 5 back in 2015.

ON THE COVER

FULL PROCESS- FOCUSED SOLUTION PAYS DIVIDENDS

Having operated a downtime-ridden plant beleaguered by excessive breakdowns, extreme maintenance glitches and low throughput setbacks, the quest to increase production efficiencies and reduce operating costs saw CNC Crushers purchase a full process-focused solution fromWeir Minerals Africa. Four years on, the decision is paying big dividends, writes Munesu Shoko .

F or 14 years, CNC Crushers has been producing aggregates out of two old gold mines located at Buffelsfontein gold mine’s Shaft 4 and 5 in the North West Province of South Africa. The quality of the dolerite rock has made CNC Crushers a supplier of choice for a wide range of road building and construction material specifications. From an operational cost point of view, rehabilitating the waste materials from the old gold mines has provided CNC Crushers with a competitive edge, especially considering that there is no need for costly operational processes such as drilling and blasting. However, these operational gains were initially outweighed by inefficient processing plants plagued by high wear on crusher liners, excessive maintenance problems and unplanned downtime due to constant breakdowns, resulting in low throughput and high operating costs. In 2015, Weir Minerals Africa presented a full process-focused

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Following the success of the plant upgrade at Shaft 5, CNC Crushers decided to upgrade its existing plant at Shaft 4 with Weir Minerals Africa’s new technology equipment.

that the quality of our product can influence plant utilisation and availability. The equipment must always be available in order to get the best utilisation, that’s the starting point,” says Steenbok. Michael Lapidoth, Product Support Manager for Trio ® and Enduron ® at Weir Minerals Africa, adds that utilisation and availability are two key parameters in aggregate production, especially considering that quarries are volume-driven operations selling low-margin product. For them to operate profitably, quarries need to keep volumes moving. “Availability is the proportion of time the equipment is available to be used for its intended purpose, while utilisation is the proportion of the time that the equipment is used for its intended purpose,” says Lapidoth. “In any mining environment, poor equipment availability and utilisation can endanger the success of the operation.” The start – Shaft 5 CNC Crushers’ working relationship with Weir Minerals Africa started at Shaft 5 back in 2015. A major pain point for the sand and aggregate supplier was the continuous breakdowns experienced with the older technology crushing equipment and unwarranted oil usage, which resulted in excessive maintenance

KEY TAKEAWAYS

45% increase in plant throughput at Shaft 5 owing to reduced downtime and improved crusher performance

60% improvement in plant production owing to maximum availability of equipment at Shaft 4

Reduced closed side setting adjustment time from 90 minutes to five minutes as Trio ® cone crushers incorporate multiple hydraulic cylinder clamping and adjustment

13% reduction in downtime related to liner changes at Shaft 4 plant

solution to CNC Crushers, initially on a trial basis, and the results were beyond expectations. Four years later, the operational challenges are a thing of the past and engaging the services of Weir Minerals Africa has turned out to be a game changer for CNC Crushers. “We have been in this business for 14 years, but we have only ‘opened our eyes’ in the past four years following our association with Weir Minerals Africa,” says Willie Crous, operations manager at CNC Crushers. Speaking about the solution, Vernon Steenbok, Genaral Manager of Comminution at Weir Minerals Africa, explains that Weir Minerals approached CNC Crushers’ operational setbacks with an integrated solutions approach. “We always approach every plant upgrade with a specific formula aimed at improving efficiency. For us, availability x utilisation x quality = efficiency. We are confident

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for replacement parts, a significant improvement from the 120 hours. The 400CVX10 hydrocyclone has proved to be more efficient than the conventional cyclone. “We used to replace pump liners regularly, and since we installed the WBH 100 pump, we no longer have pumps on the critical maintenance list. Pump problems are a thing of the past. The Cavex 400CVX10 hydrocyclone increased the mass pull to the underflow, which resulted in increased production and reduced slimes to the tailings dam. Using this new technology is paying dividends,” says Carl Crous, owner of CNC Crushers. Following the crusher upgrade, a competitor’s installed primary classification and tertiary screens were replaced with Trio ® TIO5162 (5’ x 16’ double deck inclined screens, and the final product screen was replaced by a Trio ® 4102 (4’ x 10’ double deck) inclined screen. Product range from Shaft 5 plant comprises 6,7 mm; 9,5 mm; 13 mm; and 19 mm stone, as well washed crusher sand and crusher dust. Shaft 4 Following the success of the plant upgrade at Shaft 5, CNC Crushers decided to upgrade its existing plant at Shaft 4. The plant was running old model crushers and screens with outdated technology. The main problems encountered included high wear on crusher liners, high oil con- sumption and unplanned downtime due to persistent breakdowns. The Weir Minerals team proposed replacing the old technology 4.25 ft secondary cone crusher with new technology Trio ® TC51S standard hydraulic cone crusher. The tertiary cone crusher was also changed from an old technology 3 ft to a new technology Trio ® TC36SH standard hydraulic cone crusher. With uptime in mind, the new technology Trio ® cone crushers feature a hydraulically adjusted Closed Side Setting (CSS), allowing for quick adjustment of the setting; and a hydraulic tramp relief which protects the machine by preventing uncrushable material from entering the crusher and causing damage. Willie Crous tells Modern Quarrying that with the previous old technology

ON THE COVER

Following the plant upgrade at Shaft 5, a 45% increase in plant throughput was realised, owing to reduced downtime and improved crusher performance.

Using Weir Minerals Africa’s new technology equipment has ensured greater equipment availability and utilisation for CNC Crushers.

problems and plant downtime. CNC Crushers required a solution from Weir Minerals Africa that would utilise the existing footprint and infrastructure. The first machine to be installed by Weir Minerals Africa was the Trio ® TC51S cone crusher, which replaced an old technology secondary cone crusher. Lapidoth says there was an immediate increase in uptime and reduced maintenance costs, which prompted the client to purchase a Trio ® TC36SH tertiary cone crusher. “The products quickly increased plant availability and production, while meeting the criteria of utilising CNC Crushers’ existing footprint and infrastructure at Shaft 5,” says Lapidoth. Key results from these interventions include a 45% increase in plant throughput owing to reduced downtime and improved crusher performance; reduced closed side setting adjustment time from 90 minutes to five minutes as Trio ® cone crushers incorporate multiple hydraulic cylinder clamping and adjustment; and quick and simple crusher maintenance. Additionally, Trio ® cone crushers have a larger socket assembly giving full support under both extreme and light load conditions, thus providing a longer crusher service life. Another key challenge on site was the high wear on the existing conventional cyclone and the old Envirotech ® pump – which called for replacement of liners every 120 hours of operation. “The cost here was twofold – frequent replacement of liners cost a lot of money, while the cost of downtime related to the replacement process was just too much to bear for the client,” explains Lapidoth. “The brief from the client was to increase solids to the cyclone underflow, and increase wear life on the cyclone feed pump.” To improve the process, Weir Minerals Africa provided a Warman ® WBH 100 slurry pump and a Cavex ® 400CVX10 hydrocyclone to CNC Crushers. After 1 900 operating hours, the WBH ® 100 slurry pump was still running without any need

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and 300 tonnes per hour. The crusher dust is currently the largest volume driver. To give an idea, at Shaft 4 plant, CNC Crushers is producing 1,3 tonnes of crusher dust per minute, highlighting the highly productive nature of the plant. In addition to the purchase of new Trio ® equipment, a service agreement was signed between Weir Minerals and CNC Crushers. Regular inspections are conducted by a Trio product support specialist and all machines are well maintained. Services are performed at 300-400 hour intervals. “The service agreement ensures best practice is adhered to in operating and maintaining the equipment. This helps the plant to achieve maximum availability and long operational life of its equipment,” says Lapidoth. Key results from the interventions at Shaft 4 plant include a 60% improvement in plant production owing to maximum availability of equipment, as well as a 13% reduction in downtime related to liner changes. “Another key benefit has been the improved variety of product specifications from multiple product screens. Previously this would be achieved by blending from different stockpiles using front- end loaders,” says Lapidoth. “Our start-up procedures have become quick and simple, while adjustment of the crusher CSS takes only five minutes compared with 90 minutes with the old technology crushers we used to run. The plant is just a pleasure to run and that, coupled with the right support behind us, is a winning formula for us,” concludes Willie Crous. l

crushers, they had to change socket liners after every three months. This has since been improved to 2 700-hour (12- month) socket liner replacement intervals with the Trio ® TC51S and TC36SH. “With every socket liner replacement on the old generation crushers we had before, we also had to do an oil change, putting in about 500 l on each occasion,” says Crous. “Loss of operational time due to adjustments and starting up of old technology crushers was also a major challenge for us, as it affected production output.” While bowl and mantle liner replacement cycles have pretty much remained the same at between 650 and 700- hour intervals, there is a huge difference in the throughput. With the Trio ® TC51S and TC36SH, a total of 250-350 m³ material goes through the crusher liners per hour, while 120-150 m³ per hour was achieved with the previous cone crushers. As part of the upgrade, three Trio ® inclined screens were installed, namely the Trio ® TIO5163, TIO6203 and TIH4102. The screens are capable of producing a variety of product specifications directly without the need to blend material. When we visited the site, CNC Crushers was producing five different specifications of road stone. These included 6,7 mm; 9,5 mm; 13 mm; and 19 mm stone, as well as crusher dust. By just changing the screen mesh sizes, CNC Crushers has the capacity to produce extra product specifications. The plant has the flexibility to produce between 250

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CRUSHING

I n the previous Crushing the major talking point was that, to execute the crushing process cost-effectively, it’s always important to deploy the correct crusher for the ideal application. This not only saves you time, but it will also save you money in the long run. The article also looked at whether geology was a major factor that determines the type of crusher to be deployed in an application. The focus now turns on how quality parameters influence the crusher to be deployed for a job at hand. Quality parameters in aggregate production are normally based on strength, size and shape of the end product. How does the end result help determine what type of crusher is needed? Johann Pruewasser, engi- neer at Keestrack, says to determine the most economical crusher for the article (published in Quarter 1 edition of Modern Quarrying ),

QUALITY PARAMETERS IN CRUSHING Quality parameters in aggregate production are normally based on strength, size and shape of the end product. How does the end result influence the type of crusher to be deployed? By Munesu Shoko .

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KEY TAKEAWAYS

Quality parameters in aggregate production are normally based on strength, size and shape of the end product

The final product requirement is the cornerstone of equipment selection and plant design

If optimum shaped product is an obligation, the VSI crusher is the ideal shape-producing crusher

Apart from costs, the main advantage of the VSI compared with the HSI crusher when it comes to production of a cubicle product is the consistency in the end product

An impact crusher reduces the amount of flaky material from the feed ROM and/or flakiness produced from the jaw and cone crushers.

crushers required to produce the desired product sizes in the acceptable crushing ratios,” says Ravenscroft. “The desired product shape will determine the type of crushers required. Should a high quality shape be required, an impact crusher will be necessary to get the end product into specification,” adds Ravenscroft. More quality considerations Sandro Scherf, CEO of Pilot Crushtec International, says one critical consideration is the end application of the aggregate produced. Some basic examples where shape and size or product size distribution (PSD) is critical to include are filter sands, road construction and asphalt topping, to mention a few. “Filter sands require very strict product curves. With too much fine material, the fil- ter sand turns to clay, which doesn’t allow water to flow through. With too little fine material, the water passes through too easily and particles aren’t filtered out,” explains Scherf. For road base construction, Scherf says the Colto specs on G1 and G2 base and sub-base material require at least 4-12% of 0,075 mm material, all produced from clean parent rock. “The micro fines basically act as a lubricant when compacting the road-base to ensure that you get the correct compaction levels and have a sturdy base on

job at hand, project considerations always have to start at the end. “This means that all tooling deliberations have to be informed by the quality demand of the final product, and then go step by step from the end of the process to the primary crushing stage,” says Pruewasser. Dewald Janse van Rensburg, MD of B&E International, says the final product requirement is the cornerstone of equipment selection and plant design, and certain combinations of jaw crushers and secondary crushers have proved to be more effective in achieving certain outcomes. “Customer requirements will also specify the grading envelope that must be achieved, which is the ratio between the coarser and finer aggregates. For any operation, the intended throughput rate is another key consideration in the choice of crushers and their sizes, and with commercial operations the market will dictate the level of demand to be satisfied, or the draw-off requirement for a specific project,” says Van Rensburg. Tyron Ravenscroft, Finlay product manager at Bell Equipment, says the strength of the material determines the crushing ratios acceptable to that material and how many crushers will be required to crush the run of mine (ROM) to the desired product sizes. “The size of the ROM will determine the size of the primary crusher to accept the ROM. The ROM size will also determine the number of

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CRUSHING

Should a high quality shape be required, an impact crusher will be necessary to get the end product into specification.

Scherf says this can depend on the rock characteristics and the plant layout. However, as a general rule, the HSI and VSI crushers offer the best shape. “Often a three-stage plant consisting of 1 x jaw crusher and 2 x cone crushers will also pro- duce a cubicle product. The type of cone crusher will have a significant effect on the results. A Metso HP crusher, for example, can produce a very cubicle product when utilised correctly, which a Symons type cone crusher, for example, cannot offer,” says Scherf. Due to the hardness and abrasive nature of most of the rock in south- ern Africa, Scherf says the VSI is the preferred option when it comes to a cubicle product, and would be used as a tertiary or quaternary crusher. “The main advantage the VSI has over the HSI crusher in this application, operating costs aside, is the consistency in the end product. As soon as you start feeding an HSI crusher you start having wear in the chamber, which means you require constant adjustment to achieve the same results,” says Scherf, adding that on the VSI, the wear on the rotor has a minimal effect on the product PSD, meaning you have a consistent product. Close partnership To come up with the best crushing solution for the application at hand, a closely knit cooperation between the supplier and the customer is of utmost significance. Dickson says it’s an absolute necessity, the client understands their challenges far bet- ter than the supplier does, through

which to lay the road. This can generally only be achieved with the introduc- tion of a vertical shaft impact (VSI) crusher as a tertiary or quaternary stage in the process,” explains Scherf. For asphalt topping (and high MPa concrete), Scherf reasons that it’s critical to have a cubicle shape to the stone rather than a flaky product. Flaky material is weak and can be broken by the pressure of large vehicles, while an exposed hole will fill with water and quickly form a pothole. “Cubicle material fits closer together and more compactly, ensuring that less asphalt (or cement) is required in production, thereby reducing costs significantly,” he says. Scherf adds that since flaky material doesn’t compact as tightly as cubicle aggregate does, one is left with voids or spaces between the material, which is then filled with tar from the asphalt. In hot climates the tar will soften, and this can cause deformation of the road surface when exposed to heavy traffic. “Cubicle product adds value to your end product, however, many construction projects don’t require high specification aggregate, so the added expense of shaping the end-product does not make financial sense,” argues Scherf. Shape in question If the shape of the stone is a major spec requirement, what crusher achieves the best product shape? JD Singleton, process director at Weir Minerals Africa, says if optimum shaped product is an obligation, the VSI crusher is the optimum shape-producing crusher. The same view is shared by Heath Dickson, national mining sales manager at ELB Equipment, who says, without a doubt, a VSI, and in some cases a horizontal shaft impact (HSI) crusher, will help shape up the product. Ravenscroft is of the view that an impact crusher will give the best quality shape to a stone. “An impact crusher reduces the amount of flaky material from the feed ROM and or flakiness produced from the jaw and cone crushers. It removes the brittle pieces from the stones, creating a more high quality cubic shape,” says Ravenscroft. Van Rensburg says it’s not easy to control the shape of the aggregate; different host rocks will break differently. “If for instance the material is flaky, then you can introduce specialised equipment like a VSI to break down the edges of the stone and make them more cubical,” he says. While most mining operations require ore to be crushed as fine as possible, Van Rensburg says this is not always the case. “Where fines must be kept to a minimum, there is need for less aggressive crushing, or the ore must be screened or scalped before crushing takes place to minimise further fines generation,” adds Van Rensburg. Pruewasser says every stone has a crystalline shape which is normally hexagonal. He says impact crushing systems crush the material along this crystalline structure because it is the easiest part of the rock to crush. “This always gives a better shape than crushing with shearing or pressing forces offered by cone and jaw crushers,” says Pruewasser.

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Customer requirements will specify the grading envelope that must be achieved.

A Trio vertical shaft impact crusher installed at a quarry.

their experience from working the site. “The supplier’s main function is to make the client aware of the crushing technology available to meet the client’s produc- tion needs,” he says. Singleton says as experts in crushing applications, flowsheet design and crusher maintenance, Weir Minerals Africa understands that uptime and maximum production are the primary drivers for an aggregate client’s profitability. “As a result, we believe that long-term partnerships with continuous support, as well as spares and service agreements, are the only way to run a sustainable business,” says Singleton. “At Weir Minerals Africa, we understand that the more we help our custom- ers become profitable, the more relevant we are. We do this by maintaining our machines and collaborating with clients and continuously finding innovative ways to increase their production, using their existing infrastructure,” adds Singleton. Van Rensburg says close collaboration with the customer is always essential. “For a start, it allows the supplier to understand the application in detail and to design the right solution; but it is also important to ensure that the customer receives the support they need for smooth operations and lowest cost per ton,” he says.

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CRUSHING

The final product requirement is the cornerstone of equipment selection and plant design.

on the ROM material and the desired end product requirements. “Once all this information is obtained, there are many different simulation programmes available to help determine the correct plant speci- fications needed to achieve the desired end product specifications. Bell and Finlay’s application special- ists work closely with our customers with the initial product selection and thereafter with ongoing plant efficiencies and product support because our core belief is if we help our customers succeed so will we,” he says. Scherf is of the view that selecting the best crushing solution is only the first step to achieving targets and ensuring a successful business. He says that a close cooperation between supplier and customer is critical for long-term success as operating conditions are continu- ously changing. “Nature did not mass produce rocks to the same speci- fications; the deeper you quarry the more competent and hard the rock is. Crushing conditions can also change drastically in some areas due to the rainy season. Having close cooperation means that many of these challenges can be pre-emptively addressed, by ensuring that the correct spares or screening media is in stock before the rains come, for example,” says Scherf. Scherf says when site conditions or the contract spec- ification change, the first person the customer should call is their trusted advisor from the supplier to ensure that fine-tuning of the plant can be done timeously to maximise productivity. “It is very hard to drop costs without compromising on quality, so improving the plant’s performance by 1% has a hugely positive finan- cial impact over the course of a year. A simple example is a 1% improvement on production on a 100 tph plant; over a year it would make up to 2 000 tonnes differ- ence, and that equates to 100 additional tipper trucks delivering to end-users for the same fixed operating costs,” concludes Scherf. l

Pruewasser says only if the supplier and the customer are prepared to work together closely will it be possible to determine, in partnership, the most economical crush- ing system which is able to fulfil the quality demand. Ravenscroft says it’s imperative that the customer furnishes the supplier with all the necessary information

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WHEEL LOADER EFFICIENCY – THE DRIVELINE’S INFLUENCE Wheel loaders play a huge role at quarries and their efficiency is key to overall productivity of operations. It is generally agreed that choice of a wheel loader’s driveline plays a big role in the overall efficiency of the machine. With various driveline options available, what should influence the choice of a driveline when it is buying time? By Munesu Shoko .

LOADING – WHEEL LOADERS

T he choice of a driveline is one of the principal influencers of a wheel loader’s efficiency on site. How important is the driveline choice when it comes to wheel loader efficiency? Frank Schmitt, product manager for wheel loaders and articulated haulers within Volvo CE Sales Region EMEA, says well-matched and efficient driveline components are one of the most important influence factors for a state-of-the-art wheel loader. Schmitt reasons that the choice of a driveline depends on the application – short cycle loading or load and carry applications, levelled ground or up-hill. “However, if you choose a modern powershift transmission with a lock-up function, which adjusts shift pattern according to the usage, that’s a versatile solution that fits all applications,” he says. “There are more components which are important to evaluate during the purchasing decision – for example, hydraulic system, lifting arm linkage and turning radius, among others.” Stephen McNeill, marketing manager – Alliances at Bell Equipment, says the driveline choice directly impacts wheel torque, machine responsiveness and fuel efficiency. He reasons that some of the factors that should influence a customer’s choice of a driveline in their wheel loader include machine breakout force, cost, fuel efficiency and backup support when failure occurs. To get overall control of the quality of the machine, Volvo CE develops and manufactures the driveline components in-house. “This gives us the possibility

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The choice of a driveline is one of the principal influencers of a wheel loader’s efficiency on site

The hydrostatic driveline is more efficient in short cycle loading as the power losses are not as high as with a torque converter

A key benefit of the mechanical drive is the

The Continuously Variable Transmission is a combination of a hydrostatic driveline and mechanical transmission. It’s an efficient but complicated and expensive solution

provision of high end torque at the wheels and its simplicity to maintain

According to Schmitt, the powershift transmission is a proven technology with a very long life time. “The lock-up function eliminates the power losses from the torque converter. Intelligent shifting pattern – either selectable by the operator or sensed by the machines – makes the transmission adaptable to different applications,” he says. When it comes to the hydrostatic driveline, Schmitt says this is more efficient in short cycle loading as the power losses are not as high as with a torque converter. He, however, says that as most wheel loaders are used in load and carry applications – the hydrostat is very inefficient during these applications. Furthermore, the hydrostatic driveline generates a lot of heat and, therefore, requires a lot of cooling capacity. Another driveline option is the Continuously Variable Transmission (CVT). It is a combination of a hydrostatic driveline and mechanical transmission. “It’s an efficient but complicated and very expensive solution. The lifetime expectations are not suitable for a wheel loader and early overhauls are necessary,” explains Schmitt.

to have a purpose-built engine, transmission and axles that have minimal power losses without compromising the lifetime of the components,” says Schmitt. “Nevertheless, I would say that the biggest influence factor for efficient operation is the operator. Well trained operators don’t push the throttle to the bottom all the time; they know and have a feeling for how much power they need to fill the bucket quickly while avoiding spinning tyres. Modern technologies and automatic support systems, which you find on Volvo wheel loaders, will help even an inexperienced operator to achieve good results,” adds Schmitt. Types of drivelines According to McNeill, the Bell E series range of wheel loaders has a drivetrain that comprises of a John Deere POWERTECH engine that powers a ZF powershift transmis- sion which propels the machine through the John Deere Teammate V axles. A key benefit of the mechanical drive is the provision of high end torque at the wheels and its simplicity to maintain.

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LOADING – WHEEL LOADERS

New developments As technological development

continues apace, Volvo CE now uses its Optishift in the large wheel loader range, from the L150H to L260H. The patented Optishift includes two items: firstly the lock-up function and, secondly, the Reverse-by- Braking technology. Volvo CE has improved the lock-up shifting strat- egy when no throttle is applied. The lock-up function is available even in first gear – this is a big benefit in dozing applications. Furthermore, you have a selectable automatic lock-up function between 2 nd -4 th , 3 rd -4 th or 4 th gear. “The Reverse-by- Braking control and response have also been improved. The large number of upgrades, improvements and new features continue to make the Volvo-developed Optishift the best in the industry, contributing to an overall 15% improvement in fuel efficiency,” says Schmitt. Speaking about some of the possible future developments in wheel loader drivelines, McNeill believes that more focus will be on gear shift improvements, torque convertor optimisation with lock up, as well as the development of engine torque vs. efficiency. Schmitt says today electro-mobility is in everybody’s mind. He is of the view that in future we will see more driveline components being replaced by electrical actuators – for example, transmission and propeller shafts will be replaced by electro motors at the axle hubs. “Efficient electrical actuators will allow us to downsize the engine, as we will have no power losses anymore in the driveline or the diesel engine gets completely replaced by batteries. But we are not there yet and it will take a few more years before we have sufficient, long lasting batteries and reliable off-road components,” concludes Schmitt. l

The Bell E series range of wheel loaders is driven by a mechanical drivetrain.

Volvo CE believes that in future we will see more driveline components being replaced by electrical actuators.

A key benefit of Bell’s mechanical drive is the provision of high end torque at the wheels and its simplicity to maintain.

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SAFETY

At a time when the South African mining sector is battling high numbers of fatalities at operations, members of surface mining industry association, Aspasa, have reported no fatalities across their operations for the third year running. Central to this feat is the adoption of an advanced health and safety regime that has ensured that member operations lead the way as far as compliance is concerned, writes Munesu Shoko . LEADING THE WAY TOWARDS ZERO HARM

W ithout a doubt, mining is deemed one of the most dangerous jobs in the world. The International Labour Organisation estimates that 1% of the global labour force is involved in mining. Yet the industry accounts for 5% of on-the-job fatalities. It is for this reason that a global focus on health and safety at mining operations has gathered momentum over the years as the industry seeks to get its act together. When talking about health and safety in general, it would be fair to shine the spotlight on South Africa, where the legacy from earlier attitudes to worker safety still resonates in the drive to continually improve safe mining conditions. Moving into a third consecutive year without a fatality, members of surface mining

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KEY TAKEAWAYS

Members of surface mining industry association, Aspasa, have reported no fatalities across their operations for the third year running

A key success driver is Aspasa’s strict health and safety regime which ensures highest standards of compliance at member operations

The Aspasa health and safety auditor visits about 100 member quarries every year

Out of the 102 ISHE audits done during 2017, 16 operations achieved scores of above 90%

Testimony to the spirit of continuous improvement is the constant achievement of high scores in the annual Aspasa ISHE audits by members such as AfriSam.

Another 26 operations achieved scores between 90% and 95%, while 40 other operations scored between 80% and 90%, to end on an average of 85,84%

industry association, Aspasa, are surely leading the way as far as health and safety at operations is concerned. The feat is remarkable, given that figures from the Department of Mineral Resources (DMR) still show a high number of fatalities at mining operations. While injuries decreased from 1 749 in 2017 to 1 358 in 2018, fatalities were on the rise, up from 51 to 81 during the same period. This was in contrast to the downward trend which saw fatalities falling from 112 in 2012 to 93 in 2013; 84 in 2014 and 77 in 2015; and 73 in 2016. Nico Pienaar, director of Aspasa, says he is pleased that the associa- tion’s members are playing their part in reducing injuries and fatalities as part of the industry’s journey to Zero Harm by 2020. Traditionally, Aspasa represented members in the sand and

aggregates industry only, but in recent years membership has been broadened to include all surface mines. Currently, the association mainly represents members in the non-precious metal, stone and coal industries. Success drivers A key success driver is Aspasa’s strict health and safety regime, which ensures highest standards of compliance at member operations. Members need to adhere to strict health and safety standards for them to secure and maintain membership. “Some 20 years ago we started with our Health and Safety (ISHE) Audit for the industry to ensure that our members adhere to the most stringent health and safety parameters to ensure highest standards of safety at opera- tions,” explains Pienaar. “Our stance is that we don’t talk about health and safety; we do health and safety. There is so much talk about how best the industry can get to the bottom of safety incidents on site. However, as much as we agree that talking about it is the start, we believe that execution is what really matters. We believe in doing, hence

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