Coal Preparation at Tahmoor Colliery 123
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119 特 別 COAL PREPARATION AT TAHMOOR 講 演 COLLIERY W.G.TWEDDLE TABLE OF CONTENTS 1.INTRODUCTION 119 7.1 Plant Automation 131 2.BACKGROUND INFORMATION 121 7.2 Reject Disposal 131 3.MINING OPERATIONS 122 7.3 Environmental 131 4.RA W COAL QUALITY 123 7.4 Plant Manning 133 5.DESIGN CONCEPT 124 8. QUALITY CONTROL 133 6.PROCESS DESCRIPTION 126 8.1 Mine Planning 133 6.1 Raw Coal Handling 126 8.2 Plant Product Quality 136 6.2 Jig Circuit 127 8.3 Plant Efficiency Analysis 136 6.3 Dense Medium Bath 127 8.3.1. Yield Predictions 136 6.4 Medium Recovery 128 8.3.2. Reject Analysis 137 6.5 Froth Flotation 128 8.3.3. Plant Sampling 137 6.6 Water Clarification 129 8.3.4. Efficiency Testing of 6.7 Tailings Dewatering 130 Washing Units 137 6.8 Clean Coal Handling 131 APPENDICES 139 7. GENERAL INFORMATION 131 ACKNOWLEDGEMENTS 139 Abstract The Tahmoor mine is located some 80 km south-west of Sydney in the South Western coal mining district of New South Wales. Construction of the Coal Preparation Plant was completed in June 1981. Since this time the plant has processed all run of mine production on a two shift per day basis. The plant is a nominal 300 tonne per hour single module unit. Plant design consists of jig washing and froth flotation of the fines, with the option of dense medium separation if the raw coal quality warrants the production of a middlings product. From an engineering point of view the special features of the Tahmoor Plant are:- 1. The Baum jig has 10 compartments and three elevators. This allows middlings recycling in the third elevator. 2. The Leebar bath was selected because of its capability for a low S.G. cut and its mechanical reliability. 3. The selection of an Enviroclear thickener for tailings thickening. 4. A mechanical tailings dewatering plant which includes a solid bowl centrifuge and a band press filter. Major emphasis is placed on all aspects of quality control and plant efficiency. This is reflected in the con- sistency of product and reliability in operation of the plant. 1. INTRODUCTION B.P. coal australia is a Department of B.P. Australia Limited, a wholly owned subsidiary of The British Petroleum Company London. The department is responsible for all B.P. Coal interests within Australia which comprises : Clutha Development Pty. Limited, a fully owned subsidiary and two joint ventures, Clarence Colliery and Winchester South Development. *CluthaDevelopmentPty ,Ltd. *昭 和59年6月13日 本 会 第72回 例 会 に お い て 発 表 **Manager Coal Preparation ,BP Coal Australia Limited 昭 和59年5月10日 受 理 Vo1.31,No.2(,84-夏) (39) 120 W.C.TWEDDLE (40) 浮 選(資 源処理技術) COAL PREPARATION AT TA14MOOR COLLIERY 121 Clutha Development Pty. Limited operates in three areas of New South Wales:•\ 1. The Southern Area: The southern area comprises the Burragorang Valley and Tahmoor Divisions. The Burragorang Valley operates four underground mines with coal preparation facilities at Wollondilly. Tahmoor is an underground mining operation with a coal preparation plant on site. 2. The Northern Area: The Northern Division operates two underground and two open cut mines in the Hunter Valley region of New South Wales. All raw coal is processed at Newdell Coal Preparation Plant. 3. The Western Area: This Division operates two underground mines and one open cut mine in the Lithgow region of New South Wales. The Coal Preparation Plant at Western Main processes all run of mine coal. 2. BACKGROUND INFORMATION The Tahmoor Colliery is located some 80 Km south west of Sydney in the South Western coal mining district of New South Wales. Clutha Development Pty. Limited was granted the initial exploration licence in 1970. Following exploration drilling, a mining proposal was put forward for a complex consisting of two mines, serviced by a central coal preparation plant. Construction commenced in September, 1975, on the Tahmoor East Mine with a drift at the central services site with two vertical shafts on other sites. Production commenced from the mine in September, 1979. Output was limited to 2,000 tonnes per day of raw coal until the washery was completed in June, 1981. Vol. 31, No. 2 ('84-‰Ä) (41) 122 W.C. TWEDDLE 3. MINING OPERATIONS The coal seams in the Tahmoor lease are as follows :- Total Reserves In Situ Bulli 95.6 million tonnes Wongawilli 20.4 million tonnes The Wongawilli reserves are not regarded as currently economic and are excluded from all project proposals. Current production is 1.026 million tonnes per year of raw coal which is mined by board and pillar extraction method from six continuous mining units. TAHMOOR COLLIERY MINE WORKINGS ( 42 ) 浮 選(資 源処理技術) COAL PREPARATION AT TAHMOOR COLLIERY 123 4. RAW COAL QUALITY Raw coal ash has averaged 23% to date. In general terms there is not a large amount of material found in the `middlings' gravity fraction between 1.50 and 1.80. Middlings content varies across the lease from less than 2% up to 10%. In certain parts of the lease jig washing coupled with froth flotation enables product ash speci- fication to be met at cut points in excess of 1.60 R.D. For the bulk of the reserve, however, it is necessary to extract the middlings content at varying cut points down to 1.40 R.D. to meet product specifications. In addition, the large coal fractions (plus 12 mm.) has a higher raw coal ash than the smaller coal fractions (minus 12 mm.) The large coal will also wash to a higher ash at a lower yield com- pared to the small coal. This led to the final selection of a jig as the main processing unit plus a heavy medium bath for washing the large coal from the jig when conditions are appropriate. TAFIMOOR COLLIERY CHANNEL SAMPLE SS 51 Location 202 Panel, 1OM A3 to B3 E262590 N. 1210068 Date Sampled : 5th January, 1984. Date Analysed 16th February, 1984. Sampled by I JS. Thickness 2.155 M Sample broken up by hand to•\19.05 mm•~0 SIZING ANALYSIS % Weigh t % Ash Size Fraction Cumulative Fraction Cumulative -19 .05•~0.50 mm 92.38 92.38 8.69 8.69 -0 .50 mm•~0 7.62 100.00 7.11 8.57 FLOAT AND SINK ANALYSIS OF -19.05x 0.50 MM SIZE FRACTION Vo1.31,No.2(,84-夏) (43) 124 W.C. TWEDDLE FLOAT AND SINK ANALYSIS OF•\0.50 MM•~0 SIZE FRACTION PRODUCT SPECIFICATION (Air Dried Basis) •\ Coking Coal •\Steaming Coal Ash 8.5% Ash (Nominal) 15.0% Inherent Moisture 1.5% Inherent Moisture 1.1% Volatile Matter (Nominal) 28.0% Volatile Matter (Nominal) 24.0% Fixed Carbon (Nominal) 62.0% Fixed Carbon (Nominal) 60.0% Crucible Swelling Number (Nominal) 5%-6 Specific Energy (Nominal) 29.OMJ/kg. Total Moisture (Maximum) 8.0% Total Sulphur (Maximum) 0.4% 5. DESIGN CONCEPT The coal preparation plant is a nominal 300 tonnes per hour single module. The plant was constructed by Bulk Materials (Coal Handling) Services Pty. Limited. With regard to the modular design of the plant consideration was given in design to the future requirements of additional washing capacity. Options are available to install an additional module which would only require a jig coupled with associated flotation equipment. An allowance has been made for the future addition (44) 浮 選(資 源処理技術) COAL PREPARATION AT TAHMOOR COLLIERY 125 of a dense medium cyclone section should it become necessary to produce a lower coking coal ash product. In general building layout, a concept of relatively low profile design has been achieved by the use of internal conveyors. In obtaining this, a gravity flow situation has been maintained throughout the various process sections with minimum pumping of solids. TAHMOOR COAL PREPARATION PLANT SOLIDS FLOW DIAGRAM TAHMOOR COAL PREPARATION PLANT EQUIPMENT FLOWSHEET Vo1.31,No.2('84-夏) (45) 126 W.C. TWEDDLE The plant is basically a jig and flotation plant with the option of dense medium separation of the coarse material. All run of mine feed is initially treated in a jig for removal of heavy reject material. The product after screening reports either directly to the coking coal conveyor or the plus 12 mm. material goes to a dense medium bath for further separation, if necessary. In the bath section a middlings product is removed and following crushing to 50 mm. is collected for discharge from the plant. The balance of the coking coal from the bath is screened at 50/13 mm. before the plus 50 mm. coal is crushed and the minus 13 mm. material joins the centrifuge feed. Should the total coarse material be of acceptable coking quality, provision is made to by-pass the bath completely, with the coarse product, following screening and crushing, discharging direct to the coking coal conveyor. The minus 0.5 mm. is collected from the jig water circuit for treatment by froth flotation. The recovered product from the drum filters discharges onto the coking coal conveyor. The flotation tailings after thickening are pumped to the tailings treatment plant. 6. PROCESS DESCRIPTION 6.1 Raw Coal Handling All raw coal is transferred from the underground bins by a 1.1 metre steel cord conveyor. The run of mine feed is scalped on a vibrating screen to remove all plus 150 mm. stone. The minus 150 mm. material is conveyed to the emergency stockpile area or is screened over a divergator before storage in two 1250 tonne concrete bins. The divergator sizes the coal at 25 mm.