UNDERGROUND RAIL
Goodman lithium locos
IM spoke to Simon Lewis , Global Marketing Manager at Trident SA , the global leader in underground mining loco supply , producing around 250 per year . While these have all been lead-acid battery based - the industry is now looking to transition to lithium battery due to a number of notable benefits
Q Lithium battery technology has been talked about for some time in relation to underground mining rail - why is the market only taking off now ? A Battery is not new to this market - underground mining rail both in South Africa and in other countries has long been dominated by lead acid batteries . All of the Goodman locos we produce today are either lead acid battery powered or use a combination of battery and overhead trolley line . But lead acid as a technology is much more inefficient and less sustainable when compared to lithium-ion . The reason the market has been slow to switch is mainly due to mines focusing initially on other areas like digitalisation , underground comms networks and upgrading of trackless fleets - and also that the locos already in service have incredible longevity due to their rugged design . Operators in mining are traditionally conservative and are only likely to switch to lithium for new greenfield projects , even though the lithium battery packs are entirely retrofittable and can be fitted without any major changes to the locos .
Lithium-battery powered Goodman loco at Trident SA ' s workshop in Germiston
acid . Plus of course they contain lead which is a pollutant if it ends up in landfill - and there is much more recyclable demand for lithium , though there is a well set up infrastructure for lead acid battery recycling as it is a more mature market . There are even potential second life uses without recycling - when the lithium battery comes to its end of life in mining , it may still have enough capacity to be reused for domestic / office or light industrial uses or offices , and Trident is actively exploring the possibility of how this can benefit the communities around and adjacent to major underground mines .
Q Can you outline in more detail why lithium batteries are a more efficient option for mining rail underground ? A Mining customers today buy two lead acid battery packs per loco with one for active use and the other being charged for the next shift - but it takes eight hours on average to charge - meaning it is being charged for the whole of the active shift . Lithium packs have sufficient power storage and a short enough charge time of about two hours for just one for be used with no need for a standby , as the charging time is concurrent with the shift change . Not only that , but our innovative lithium battery charging can be done via a plug in system as it is integrated - lead acid batteries need to be removed and charged in a large charging station , which takes up valuable space underground with of course extra excavation costs . Last but not least our lithium battery packs will last ten years or more - double that for lead acid . The plug and play nature of lithium packs also means less handling of the batteries and in the case of lead acid that means less risk of injury . The lithium packs are also narrower so they tie up less space on the locomotive . Lead acid batteries have to be removed for routine loco maintenance and inspections of braking and other systems , whereas with a lithium battery loco this can be done via access doors on each side of the pack , without the need for removal . We have estimated this reduces handling by as much as 85 %.
Q What is the sustainability argument for the switch ? A While they are still safe to use , lead acid batteries can release toxic gases and fumes if there is a spillage , mainly from release of sulphuric
Q What success have you had to date and what has the feedback been like ? A We have about 30 battery packs out there in use in mines today . This includes installations on locos in the newer shafts of some of our largest customers like Sibanye-Stillwater and Harmony Mining . There is also a lot of interest in countries with extensive underground mining rail systems like Peru and Mexico . The technology can be applied to our full loco ranges which includes 3 t , 4 t , 5 t , 6 t , 8 t , 10 t , 13 t and 15 t as well as 20 t combination units . Operators of the locos report feeling more sustained power delivery over time – this reflects the fact that over the life of the lithium battery , the voltage remains high , which means that operators do not feel the effect of motors losing speed , because the capacity of the battery is maintained . Plus as charging does not take a whole shift , operators are often able to start and finish their allocated shift quicker .
Q What about real time management of the battery systems ? How is that carried out ? A Our lithium battery modules are “ smart ” having a BMS ( Battery Management System ) which monitors the array of modules detecting faults and failures and instituting on-board routines to ensure the batteries are protected and performing optimally . The unit is modular and also plug and play where individual modules identify themselves as problematic via the BMS and are easily swapped out . The battery performance data is also captured by the underground mine WiFi networks and relayed to the operations management team on the surface .
How is the locomotive more efficient ? This is partly due to more accurate control management through use of the permanent magnet AC motor and high frequency 3 phase inverter , all controlled by a VCU which supervises sub-system operations and monitors user input and user feedback plus is in control of all safety features and executable safety actions are executed by the VCU . A controller area network communication interfaces with third-party systems . A human machine interface ( HMI ) provides feedback to the user with all the sub-system information . As always with conversions , dealing with available space was an issue , and not just the space itself to fit the components – it is about doing this but in a way that still allows optimum service access . This was all down to detailed design and planning , including phased testing of all the integrated systems plus utilising the most compact components available , Marais said .
The locomotive at Sibanye is in its final test stages underground . The project has been a bit delayed due to the pandemic and then some union strikes . Marais told IM : " We are however satisfied with the results so far and have implemented the system on a trackless electric utility vehicle as well . Currently we are busy with the commercialised version to be able to go to market . Additional units we are planning to roll out are 10 , 15 and 20 t locomotives ."
IM
14 International Mining | JUNE 2022