African Mining July - August 2019 | Page 42

Operations Wood in the good old mining days The use of timber in mining dates back to the golden days with discovery of gold, coal and other min- erals, writes Dineo Phoshoko. Timber was predominantly used as pillars in underground mines to sup- port mines from caving in – African Mining unpacks its various uses in the mining industry. A n article by MU Ozbay, JA Ryder and AJ Jager titled ‘The design of pillar systems as practised in shallow hard-rock tabular mines in South Africa’, explains that pillars have been used as stopes since the early days of mining. This article appeared in The Journal of The South African Institute of Mining and Metallurgy (SAIMM), where the authors give a technical overview explaining that the need to use pillars in a mine is determined by prevailing considerations of rock mechanics at shallow depths. An example of such mechanics are large tensile stresses in the hanging wall and geological weaknesses in the hanging wall rock mass. sawed timbers which are primarily used for horizontal supports, mainly headers and half- headers. In his article Knutron also mentions additional uses of timber in an underground coal mine, which includes mine ties, floor planking, wedges, crib blocks, construction and repair as well as other smaller uses. In coal mining, timber is used as a support measure for an open coal seam. This is according to Robert Knutron in his article, ‘A look at the mine timber market in the Appalachian Bituminous Coal Region’. “For this purpose, round, split, and sawed timbers are used,” Knutron writes. Knutron adds that, as the coal is extracted from the coal seam, roof support timbers are set. Depending on the mine or area in the mine, mine ties will be laid, and the flooring extended, all of which use timber. It is important to note that different mines may have different timber requirements because of the different mining methods they may employ. For example, a mine using a rail system for hauling will require wooden mine ties, whereas a mine using a conveyor for hauling does not. Knutron distinguished between two types of timber and their different functions: first there are the round and split timbers which, according to Knutron, are generally used for upright supports. The second type is “Timber is used mainly in mining support systems to support the walls and rooves of extraction tunnels,” says Hayley De Haas, customer relationship manager at Merensky Timber, a longstanding supplier of sustainable lumber in South Africa. She added that many mines also use gum planks as utility boards for shuttering, walkways, cages and underground bridges, particularly in platinum mining. Timber planks are used to provide roof support in a corridor underground. 40 AFRICAN MINING JULY - AUGUST 2019 Underground mining is dangerous in its nature and, as a result, it is important that the timber used, regardless of the application, is up to standard and meets certain specifications. Knutron outlines three main specifications. Firstly, the timber must be suitable for the intended use in the mine; it has to be manufactured to the correct standards and it needs to be structurally sound. ‘Most mine timbers are used to support the mine roof. Therefore, strength qualities are most important in mine timbers. Other qualities such as durability, elasticity, and ease of construction are also important,’ he writes. Treating timber is important to ensure that the timber lasts for as long as possible. This is not only applicable in timber construction, but also in timber used www.africanmining.co.za