FIELD VISIT TO BOGALA GRAPHITE MINE PVT LTD, SRI LANKA REPPORT
8/16/2011 SEMESTER 4 UNIVERSITY OF MORATUWA
NAME: INDEX NO:
W A H A ABEYGUNASEKARA A BEYGUNASEKARA 090801M
INSTRUCTED BY: DATE OF SUBMISSION:
MR. HEMALAL PANAGODA 15/12/2011
Contents Introduction .................................................................................................................................................. 3 Location ......................................................................................................................................................... 3 History ........................................................................................................................................................... 4 Geology of Bogala ......................................................................................................................................... 5 Industrial Importance of Bogala Graphite .................................................................................................... 6 Mining process .............................................................................................................................................. 7 Main challenges faced by Bogala Graphite Mine Pvt Ltd. .......................................................................... 12 FUTURE OF GRAPHlTE INDUSTRY ............................................................................................................... 12
Introduction This is the report prepared after participating to the field visit to Bogala Graphite Mine Sri Lanka Pvt Ltd alng with some further readings about Bogala Graphite Mine Pvt Ltd. This field visit was organized by Mr. Hemalal Panagoda, one of our senior lectures in the department of Earth Resources Engineering, on behalf of us. Objective was for us to get an overview about an underground mine layout and the activities carried out there, before proceeding with the lecture series under the module Rock Blasting and Mine Development
Location Bogala Graphite mine is located in the village named, Arugammana in the Southern Province Sri Lanka. Coming from Colombo along the Avissawella-Kegalle Road one could reach the mine by urning off at the Kotiyakumbura town and find the mine which is l ocated in Aruggammana. The Bogala graphite mine is located about 65 miles eastward from Colombo with a mean elevation of ~150m from mean sea level.The climate is tropical, hot, and humid throughout the year with annual precipitation exceeding 4m.
History Graphite Mining th
In the international trade Graphite name appears after the 16 century, mainly with reference to Germany and Siberia. Subsequently more other countries have entered to the industry of Graphite Mining, where occurrence of Graphite in Sri Lanka has been only heard after 1675, during the British Colonial period. Graphite has been one of the most i mportant exports same as Tea, Coconut and Rubber over a period of more than 200 years. Though currently it is ranked at a very low level among the major exports in Sri Lanka, during st the boom period of the Graphite mine industry in Sri Lanka i.e. during the 1 2 decades in the 20th century, the Graphite Production in Sri Lanka was to represent even more than 35% of the st world’s Graphite consumption. It was due to the higher demand for Graphite created by the 1 World War and some other factors like extremely high purity, low mining cost and large production from more than 3000 shallow pits all over the Southwest and the central part of the country. During this time the mining method used, were very primitive due to the restrictions created by the lack of technological knowledge, mining professionals and risk capital. Also it was because of the eagerness of making quick money. This is believed to have caused an extensive damage to the ore body and made major portion of the ore deposit is to be left unexploited. Sri Lanka has been one of the leading suppliers in the Graphite industry until 1920 where Sri Lanka has been represented a 20- 35% of the World’s Graphite Production. But after finding 40%C low grade Graphite from numerous large reserves of surface deposits in the countries like Republic of Malagasy, Korea, China and Mexico, a dramatic drop was marked in the Sri Lankan Graphite Mining industry, where all these other countries had a competitive advantage over the Sri Lanka. Where, in Sri Lanka the production was involved with extensive labour, extensive deep mining methods and the inability of applying mechanized stoping methods which resulted nd in low level of production and higher mining costs. During the second world war the 2 phase of the boom was occurred but it was also a temporary one. Highest ever export tonnage was recorded in 1962 as 33411 Metric Tons Second highest ever export tonnage was recorded in 1942 as 27734 metric Tons Source: PROCEEDINGS OF THE SEMINAR HELD ON 20 MINE PREMISES.
TH
JULY, 1991 AT BOGALA GRAPHITE
Bogala Mine After the dramatic fall in the Graphite mining industry in Sri Lanka, thousands of small pits where graphite mining was carried out, were abandoned and only 3 major mines were left operative: Bogala, Kahatagaha and Kolongaha, because they had been developed with modern machinery and skilled labour during the boom period. And also these have been given with the technical support of mining prfesssionals of local and foreign nationals d uring 1950’s. Bogala mine has been started in 1860’s as a set of few scattered pits. In 1950’s it has been developed upto international standards which resulted its production to increase from 25%65% from the Sri Lankan total Graphite production. Subsequently these pits had been developed as 3 separate mines extracting graphite from 3 major veins names Karandawatta, Mahabogala & Punchibogala. They were owned by A. Fernando Alias known as “Kathonis Bass”. Later he named all 3 together as “Bogala Mines”. Then it was converted to Bogala Graphite Ltd which was managed by the members of the Fernando family.
Geology of Bogala The unique vein-type graphite deposits of Ceylon occur in high -grade metamorphic terrain. In the area of Bogala graphite mine 5 main lithological units have been identified: Biotitehornblende gneiss, Garnet gneiss, Silicified gneiss, Charnockite and Pyroxene gneiss. The first three are dominant; the last two are of minor importance. In addition, a few small lenses of calc-silicate gneiss and occasional small pockets of coarse pegmatites are present.
The direction of veins is strongly controlled by the two major regional lineation directions; veins with a third direction are also present. The veins are very irregular in length, width, and local altitude and contain only minor amounts of other minerals than pure graphite. Each vein is made up of a number of parallel graphite sheets oriented parallel to the vein. The graphite is obtained from the surrounding carbon-rich sediments and transported in the solid phase. The graphite accumulates along the relatively low-pressure zones of fractures. Each graphite sheet within the vein represents a period of pressure release along the fracture.
Industrial Importance of Bogala Graphite The unique vein type graphite ores are the most valuable inherent feature found in Sri Lanka, whereas the entire graphite production is from this source. This variety is very much rare in the other parts of the world, which has given Sri Lanka a competitive advantage over the other countries all over the world, which are involved with the Graphite production. Consequently, Sri Lanka has become almost all the time to be the only country supplying high grade graphite in the form of lumps and chips whereas other countries cannot do so.
But, there are a few drawbacks involved with the vein type graphite deposits: Veins are narrow, so that extending to deeper levels which results the mining costs to be very high. The production capacity becomes low because of the requirement of expensive underground mining methods. Though number of vein type deposits are abundant in the SW quarter of the country, only a very few of them have being mined.
In spite of world competition, Ceylon graphite still enjoys a great demand due to its unusually high purity and unique physical properties and its occurrence in sizable, coherent lumps. Its one constant, strategic use is in carbon brushes for electric motors, where no other type of graphite does as well. For this reason, the Ceylon graphite has been classed in the United States as a strategic mineral. The annual production of Ceylon-Graphite, is in the range of 10,000 tons, whereas about two thirds of which comes from the Bogala graphite mine
Mining process The major activities undertaken by the Bogala Graphite Mine can be listed down as follows: DIRECT OPERATIONS:
Drilling of rock & ore
Blasting of rock & ore
Loading of rock & ore
Transport of rock & ore
Transport of men & material into and from mine
Erection of underground supports
INDIRECT OPERATIONS:
Water and drainage management
Draining of gasses (cod mines)
Mine ventilation
Mine lighting
Mining method:
At Bogala the mineral deposit is of vein type. The ore body at Bogala consists of three major and several minor sub-vertically dipping graphite veins surrounded by high metamorphic rock. The horizontal extension of the major veins is about 130 m to 300 m with thickness varying 0.28 meters to 0.98 meters and exceptionally several meters. Therefore underground mining method has been occupied. Access:
At Bogala, access to the mine is by two vertical shafts in series. Two electrically driven winders drive the cages in these shafts which transport men & mineral to and from underground and underground transport is by mine cars - In mining operations the winders are used for hoisting material to and from underground. The winders are selected in considering the expected capacity, the speed, pay load and the depth. Another important aspect under consideration is that the durability which is very much essential since the mine grows deeper and deeper as the production is carried out.
Safety:
Following factors are under consideration with regard to safety in the Mine.
over speed protection protection against sudden power failure protection against over winding safety brakes & service brakes
Hoisting:
At Bogala, for hoisting, two single drum hoists are used one at the surface and one at 72 fathom level. This is a case of multiple hoisting. The capacity of lower capacity shaft dominates if there is no production above the higher capacity shaft level. The hoist rope is the most important component of the mechanical system. In selecting the required rope ratio of diameters of rope, required safety factor, breaking strength of the rope, depth of the shaft, weight per foot of the rope are concerned. Tunneling:
At Bogala Mines, rock tunnels are excavated from the shaft to intersect the three major graphite veins. The tunneling is a sequential cyclic operation, where the involved activities are the drilling of rock, loading the drilled holes with explosives, blasting, mucking. Different types of blasting patterns (designs) are used with Burn cuts and Wedge cuts. The required type is decided mathematically and adjusted to get the maximum pull out, good fragmentation, minimum vibration and damage to neighbouring areas by trial & error. Good results are achieved by the improved experience in rock blasting. Use of electric delay detonators gives good breakage and good fragmentation and vibration and damage could be controlled. There is a delay in mili-seconds in blasting and each round fire after an interval of time. Removal of debris is done manually at the mines but mechanical equipment could be made use of. The loaded trucks are hoisted to the surface or where it is required. Drilling:
Drilling machines used most commonly are the Air leg type machine and the Jumbo drills. These machines are normally operated by compressed air. The correct pressure of air is a major concern. Water is used as the flushing medium which is used to cool the drill bit and wash the rock particles out. Normally at the mines 5' or 3' holes are drilled i n the rock, 30-35 holes for a tunnel face and for the ore body. Few holes are drilled if the ore is soft if large amount of explosives are used ore dilution will occur. The selection of drill bits depends on the hardness of the rock. The machines are maintained in good condition to obtain maximum efficiency. At Bogala S.L9 G drilling machines, are used with integral drill steel for rock drilling.
Explosives and Initiation systems:
80% gelatine and 60% gelatine are used with safety fuse and plain detonators for cross cutting and driving. In shaft sinking, electric detonators are used for safety reasons. 3
Explosive consumption for cross cutting and shaft sinking is approximately 3 kg/m . The consumption for driving and winzing is much lesser than that for cross-cutting and shaft sinking. General mine-layout:
Initially completely concrete lined twin cage rectangular main shaft sunk from the surface to 130 m level. From this level sub shaft is sunk to 307 m level and it is kept deepening. The working levels are spaced at 30-35 m vertical intervals. The extraction is below 130m levels. Since the foot wall tunneling of the main drives was found to be expensive, the main drives have been established in the graphite vein itself. By this system, the cost of the drives has been recovered by the graphite extracted in the process.
Proto-type displayed at the entrance of the Bogala Graphite Mine
Tunneling supports:
The roofs and walls of the main drives are timbered or concreted to hold back the roo f graphite from coming loose. Development of veins:
Below 130 m all development work are in these main veins namely Na, Mee and Kumbuk. But at the 130 m level over 1300 meter of cross cutting has been carried out in order to intersect vein in northern and southern boundaries of the Bogala Mine. Developing the known veins involve driving 1.8 m x 2 m tunnel in the veins and winzing 2m x 4m connection between main levels Winzes:
These are at 35 m interval distance along the drives. One winze is divided into 2 compartments: one ladder compartment and another hoisting compartment which is used as haulage way and a chute for graphite and waste rock.
Transportation:
The ore and the waste rock transportation at Bogala mine could be broadly classified as follows.
incline hoisting in winzes
level transportation by mine cars
vertical cage hoisting of mine cars
Incline hoisting is carried out mainly at levels below 410 m level and in winzes. Ore from stopes are loaded into kibbles with bottom opening doors which are placed on trolleys, hand trammed to the inclined winze where it is hoked onto a hoisting rope and hauled to the upper level. This 1
is then emptied into 3 mine cars, hand trammed to shaft station and hoisted to the surface via 4
sub shaft of depth 410 meters. In this shaft double deck cage operates which hoist two cars at a time. Once the mine cars reach the surface, they are taken for the separation of the stoped ore into sizes over 3" and under 3".
Ventillation:
Bogala Mine has a forced ventilation system operated by two 250 HP ventilation fans installed at the surface. This system along with the natural ventilation current provides a reasonably cool working environment. Efficient air flow is obtained by the booster fans installed underground. In the ventilation system the important functions are
Quantity of air blown in, depending on number of workmen
Air speed without disturbing the dust
Removal of air contaminated with blast fumes.
Underground Mine Support:
These are essential elements in maintaining adequate stability in the surrounding ground while the extracting process is carried out. Mining at Bogala requires Timber, Concrete and Steel supports to keep the mine stable to achieve safety in the working environment within the mine.
Processing of Graphite:
Objective of processing is to bring the stoped ore into a marketable product as per the requirements of the customer, by removing or reducing unwanted constitutuents in the original ore to the specified percentages such as particle size and moisture content etc. in brief, processing of Graphite is to maximise the carbon recovery.
Methods of upgrading:
Bogala deposit could be considered as vein type complex in which the mostly chosen methods of upgrading are visual, density and physical methods. Separation of value in this mine is done in three stages. That is for 90% and above carbon grades, by using visual methods. For 70% carbon to 90% carbon grades, i t is by adopting density methods. And for below 70% carbon grades, physical methods are used. Value adding to the minerals is done according to the buyers specifications. Most of the buyers are very particular on specification as they are professionals. For an instance, in Germany they use graphite in manufacturing brake liners. They insist for 1.7mm to 0.5 mm in grain size and 97% - 99% carbon. In Japan they use Graphite 80%-83% powders 300 # (mesh) as mould wash.
Main challenges faced by Bogala Graphite Mine Pvt Ltd. As graphite is used only for certain industries, advertising in mass media will not give the best results. Most suitable way of sales promotion for this type of product is personal selling by visiting individual customers which will need much of effort to be put on.
The main competitors are China, Madagascar, Norway and Canada. The success of small graphite producers like Bogala depends on how fast it could adjust its prices to changing situations in the outside market Our present market share is less than 1% and so that Sri Lanka cannot play a major role in determination of world graphite prices. Sri Lanka will have to determine the price based on the demand and supply on Ceylon graphite.
FUTURE OF GRAPHlTE INDUSTRY According to the Management of Bogala Graphite Mine Pvt Ltd.Ceylon graphite reserves are limited, compared to estimated world deposits of 1000 mill ion tons. Therefore, the only way we could develop this industry is by developing new products which are required for graphite based industries. At present, we export standard products which are further processed overseas. We need to engage in market research to identify, 1. New specifications 2. the present demand 3. the customers 4. prices and to find out ways and means to acquire the required technology to produce such new products.
