Diamond core drilling for narrow vein graphite exploration - as practiced at Bogala Mines, Sri Lanka (A Case Study)

The vein type graphite deposits which are rich in carbon found in Sri Lanka occur in metamorphic rocks as narrow steeply dipping veins. In Sri Lanka, generally these graphite deposits are explored by diamond core drilling technique. This technique has revolutionized the mining industry and directly resulted in the discovery of many minable ore bodies that would otherwise have gone untapped. Generally in this technique, possible ore bodies (veins) are explored by drilling a series of exploratory drill holes according to a pattern of drill holes designed by a competent geologist. After receiving core samples and related data sheets, core logging activity is carried out by the geologist for each and every bore hole. It is usually one of the last stages of exploration, and with data taken from core logging can be used to interpret 3-dimentional view with the support of software like Surpac. Finally it would be possible to determine whether the prospect is economically viable or not for mining. This paper looks at the suitability of diamond core drilling technique practiced in exploring narrow graphite veins in Bogala Graphite Mines of Sri Lanka and will discuss in detail pros and cons of the applying method