Chemical Technology May 2015

Chemical Technology • May 2015

Multotec’s intimate understanding of miner-

als processing and handling applications,

coupled with its flexibility in being able to

offer its customers fit-for-purpose solu-

tions, has resulted in a repeat order for two

overbelt magnets sold into a coal mining

application in the Witbank/Middelburg

coalfields. “This order follows on from the

successful commissioning two years ago

of two overbelt magnets at another coal

mine in the same group,” Willem Slabbert,

Process and Applications Manager at Mul-

totec, says.

“Multotec has a good standing within

the Witbank/Middelburg coalfields area,

where our products are supported by our

local branches,” Slabbert says. Comment-

ing on the latest order, he explains that the

application is to remove tramp metal from

run-of-mine material in order to prevent it

from entering coal gasifiers.

“This is a critical application as the coal

gasifiers have very stringent tramp metal

removal specifications,” Slabbert says.

Tramp iron traditionally removed from coal

carrying conveyors includes sections of con-

tinuous mine core breaker teeth, conveyor

belt idlers, belt joints, wire, roof bolts, metal

plates, slings, picks and pick cases, cable

hooks, expanded metal, tools, tin cans and

other such objects.

Multotec supplied the original two over-

belt magnets in September 2012, with

the latest order representing the second

phase of an ongoing expansion project.

Stuart Cullum, Process Engineer, explains

that the width of the conveyor belts in this

coal mining application is 1.8 m, with the

overbelt magnets themselves being 5.1 m

wide and 2.45 m high. They incorporate

the latest technical specifications of the

client, including pulley design, control and

instrumentation.

The overbelt magnets are suspended

over the conveyor on gantries for easy re-

moval for maintenance purposes. Features

include an automatic belt-driven self-clean-

ing system that dumps the tramp iron into

collection bins at the side of the conveyor.

The latest two overbelt magnets were

transported to Mpumalanga on lowbed

trucks, and weigh 28 t each without cooling

oil. The latter is added once on site using an

oil tanker, with a final total weight of 33.7 t

for each overbelt magnet. As per client

safety specifications, the overbelt magnets

have eight safety chains rated and certified

for a load of 16 t each. This is double the

normal requirement, with four chains rated

at 8 t each being the norm.

Slabbert confirms that these are the

largest overbelt magnets available in the

Longi-Multotec range. “Through our partner-

ship with Longi, Multotec now has access to

a comprehensive range of off-the-shelf air-

cooled overbelt magnets for underground

tramp metal removal, with the option of

flame proofing.” Having a standard range

on hand means that Multotec can meet

customer requirements far more quickly, as

this reduces lead times significantly.

For more information contact

Bernadette

Wilson on tel: +27 11 923 6193, or

bernadettew@multotec.com,

or go

www.multotec.com.

Two overbelt magnets from Multotec delivered to coal mining application

Longi-Multotec overbelt magnets are engineered to effectively remove even the most challenging

tramp metal.

Longi-Multotec overbelt magnets are designed according to specific applications criteria.

Giant leap in copper leaching technology

A new leaching technology from FLSmidth

can increase copper output by 3%, according

to a recent report. That would mean an extra

USD40million per year for an average copper

mine with primary sulfide ore.

The top ore layer of an open pit copper

mine is easily processed using heap leach

in tandem with solvent extraction and elec-

trowinning to produce copper cathodes. The

copper mineral most predominate in mines

is however chalcopyrite (CuFeS

), a refrac-

tory sulfide mineral that is found deeper in

the mine. Consequently, mining companies

struggle to maintain copper production dur-

ing the transition from oxide ore to sulfide

ore as open pit mines reach the later stages

of development. Mining companies also

struggle to recover the copper from very low-

grade concentrates and from concentrates

contaminated with arsenic.

FLSmidth recently filed patents for a

new hydrometallurgy process called the

FLSmidth

Rapid Oxidative Leach that can

economically remove the passivation layer

of primary sulfides and thereby allow the

extraction of copper. The technology operates

at atmospheric pressure and temperature