High maintenance30 September 2021
Mining companies have become good customers of tower crane manufacturers, appreciating this crane type’s benefits over others when it comes to maintenance jobs. Sotiris Kanaris reports.
A tower crane is one of the first machines purchased by a mining company for a new open-pit mine, as it helps with its construction. Once operations start, the tower crane is used for maintenance activities. Depending on the size of the reserves and the crane’s maintenance, it can remain on site for decades.
Henning Köhler, head of tower cranes division at Liebherr Chile, says tower cranes predominantly assist with the maintenance of flotation tanks. Until recently, gantry cranes were the lifting equipment of choice for this job.
Köhler says the first time a Liebherr tower crane replaced a gantry crane in a South American mine was only 12 years ago. “Before that the tower crane was never considered by the mines as an alternative. The tower crane is an option in specific open-pit mines according to the mines’ production processes.”
Since then Liebherr has sold many units directly to mine owners and big mining developers (such as Bechtel and Fluor) in Chile and Peru. “We basically managed to replace the gantry crane with our tower crane concept over the years, since the tower crane is clearly the best and most economical alternative,” Köhler highlights.
He explains that tower cranes are the most economical alternative because they have a lower monthly operational cost and higher lifting speeds compared to other cranes, low energy consumption and require low spare parts exchange. Other benefits of this crane type, cited by Köhler, are the high earthquake and wind speed resistance as well as its very long life cycle.
South Africa-based Comansa dealer Tower Crane Services (TCS) has supplied dozens of tower cranes to mining companies in Africa. TCS finds that one of the main advantages of tower cranes over other lifting equipment is their long reach. It says that when a gantry crane is used for tank maintenance, its work is limited to the tanks, whereas a tower crane can service a much bigger area. The other advantages are the small footprint and high lifting capacity.
TCS’s customers use tower cranes to replace motors, gearboxes and water pumps; to service screens (a clogged screen can weigh up to 15 t); and to lift liners into position for the mills.
Tower cranes have been purchased by companies involved in the extraction of gold, copper, platinum and graphite and other minerals. The most popular tower crane types for mining applications are flat tops and hammerheads.
Sáez has delivered a number of units to mining companies in Africa in recent years. Its sales representative Juan Ballester says that for gold and graphite mines, they have mostly supplied the TL 55 five tonne flat top model. “On some occasions we have supplied bigger flat top cranes like the Sáez TLS 75. However, our clients have never requested loading capacities of more than 10 tonnes.”
Comansa flat tops can be found in mines in South Africa, Ivory Coast, Democratic Republic of Congo, Ghana, Lesotho, Zimbabwe, Mali, Guinee, Zambia and Mauritania. TCS has sold cranes with capacities ranging from 5 t to 48 t. Most recently, a 10t 11CM185 was erected on DRDGold’s site in Carltonville, South Africa. The highest capacity unit, the 48 t 21LC750, was purchased by Kinross Gold for the Tasiast gold mine in Mauritania. Javier Militino, group marketing manager at Comansa, says the capacity required depends on the type of work the crane is going to do on site.
Comansa cranes are also used by mining companies in Latin America. A 16CM220 was supplied to the Lundin Gold mine in Ecuador and a 11LC132 model to the Antucoya mine in Antofagasta, Chile.
In Latin America, Liebherr’s Köhler has identified a trend towards larger tower cranes with higher capacity, tip load and radius. He says that in 2009, a 630mt crane was the biggest in the region used by the mining sector, now the biggest one is the 1250mt 1250 HC 50. “There are six operating in Chile and one in Peru,” Köhler adds.
The 1250 HC 50 hammerhead tower crane offers a maximum capacity of 50 t, maximum hook height of 79 m, maximum radius of 81 m and 12 t tip load. The latest unit delivered was to Anglo American for the Quellaveco mine in Peru, while another 1250 HC 50 was recently erected in the Quebrada Blanca mine. This mine is situated close to the port city of Iquique in the Atacama desert in Northern Chile at an altitude of 4,400 metres.
Köhler tells Cranes Today that Liebherr is now participating in tenders for 2000mt up to 4000mt tower cranes for mining projects in Latin America. The manufacturer has also recently delivered a tower crane to the Caribbean for a mining application. A 1000mt crane was purchased by Canadian mining company Barrick for a mine in the Dominican Republic.
Speaking about the Australian market, Andrew Coffin, cost and engineering manager at lifting equipment provider and Jaso distributor Titan Cranes, says there are not as many tower cranes used in mines as they would wish for as a tower crane provider. He says that those tower cranes found in Australian mines are usually of high capacity owing to the scale of plant and machinery used in mining applications. “They often operate on travelling bases to give better coverage of the immense real estate involved,” Coffin adds.
Tower cranes in mines are often exposed to extreme weather conditions and dust by products, which can cause damages to the structure and components.
Coffin says the often caustic environment on mine sites with dust by products prevalent, necessitates a maintenance schedule far exceeding industry standards. Titan Cranes combats the impact of the environment by implementing an upgraded paint specification and cleaning regimen.
TCS says that dust can block the drainage holes, especially in the slew gearbox area, creating corrosion. Where it can, the company replaces the bolts with ones made of stainless steel.
High temperature variations, like the ones in Atacama desert in Chile, can also be an issue. For this reason Liebherr equipped the electrical cupboard of its tower crane operating there with an extra AC system.
Juan Ballester says the weather conditions at the mines in Africa to which Saez supplied cranes to, are very hot and dry (like in the Malian desert) or very humid (in the Nigerian jungle). “Most of our clients only request for the motors and inverters of the crane to be tropicalised, which is easy to do. Some other times, when they forecast a lot of dust in the air, the clients want the motors and electrical cabinets of the crane to be of isolation grade IP65, making it quite hard to get.
“We only found one supplier of tower crane motors that accepted to build the motors of IP65 rating, because the more filters we put on the motors, the less fresh air goes into them, and the harder it is to cool the motors down. But I have to say that we have been successful in supplying cranes with IP65 rating and, after years of use, the cranes are behaving exceptionally well.” Recently, Saez sold a TL 55 five tonne capacity crane with IP65 isolation rating to a graphite mine in Mozambique.
Most mines are located in remote areas and this makes crane delivery and erection challenging. On some occasions, the tower cranes as well as the mobile cranes used for the erection arrive from another country. Ballester says the mobile crane used to erect the TL 55 5T in Mozambique was mobilised from South Africa. “It wasn’t easy, but we finally got the crane erected and working.”
The remoteness of these sites also creates problems with after sales service. “The hardest thing to do is often to provide the after sales service to these cranes. We have always relied on two external companies to erect and provide service and maintenance for the cranes that we sell to the mining industry. However, since March 2020, sending engineers to other areas of the world has been extremely complicated, due to Covid-19 restrictions.”
In 2020, many crane manufacturers saw their revenues fall because of the effect of the Covid pandemic on orders and production. The mining industry had a different experience.
PricewaterhouseCoopers’ Mine 2021 report, published in June, says mining is one of the few industries that emerged from the worst of the Covid-19 pandemic economic crisis in excellent financial and operational shape. “In fact, 2020 was a banner year for the mining sector,” the report highlights.
The report focussed specifically on the world’s top 40 mining companies and analysed their performance. “Compared to 2019, net profit was up 15 %, cash on hand rose 40 %, and market capitalisation increased by nearly two-thirds. And things are expected to get even better for the world’s biggest mining companies. Our 2021 forecast indicates that the Top 40 will report record-high revenue and EBITDA levels (in this report’s 18-year history) and the second-highest net profit.”
The strong financial performance may lead to higher investment in equipment by these companies in the near future. Despite the challenges associated with serving this industry, the tower crane manufacturers are enjoying increased demand. With more mine owners and developers understanding the benefits of using this crane type for maintenance jobs, it is clear that the number of cranes erected in mines around the world will increase.