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Show UK - BICC Metals Limited operates an electrolytic copper refinery with an anode casting facility taking its raw material from various copper scraps and blister copper. These materials are melted in a reverberatory furnace before being continuously cast into anodes. The initial use of oxygen in the reverberatory furnace was via underf1ame lances fitted to two of the three burners. At this stage the charge weight of the furnace was 200te and the objective of using oxygen was to reduce the energy requirementltonne of materials. Table 4 shows that the energy/tonne was reduced by some 24% for an oxygen consumption of 40m3/ tonne. Three years ago BICC was faced with the need to increase its melting capacity to 300 tonnes/day. Two reverberatory furnaces were available, each of 200 tonnes capacity, fired conventionally with e:ither heavy oil or natural gas, and it was normal practice to operate only one of the furnaces at a time on a 24-hour cycle consisting of a sequence of: charging, melting, blowing, poling and casting. The molten metal was cast into anodes at the same time each day, and it was desired to retain this working practice. BICC concluded that it was uneconomic to operate both furnaces simultaneously at reduced output and opted for uprating of one of the units to produce the required 300 te/day. In order to meet this increased productivity level a higher rate of energy input was required and this was a determining factor in installing an oxy-fue1 burner with associated higher flame temperature. The final burner configuration was a central oxy-fue1 burner of 450 th/hr capacity with two air-fuel burners of 200 and 340 th/hr rating. The oxy-fue1 burner was initially designed to operate on either heavy fuel oil or natural gas but was found to generate unwanted noise levels when operating on natural gas due to compromise design to handle two fuels. Separate burners are now available to maximise changes in fuel costs. Burner changeover is accommodated during casting. Results were dramatic in that the required 50% output increase was attained from the outset with melting rates increased by some 80% to 25 te/hr. Overall energy input averages 1ess~than 30 th/te for the total cycle and 55m~/te of oxygen is used. The benefits to BICC from this installation are highlighted as: 1. Major increase in productivity for a relatively small capital outlay. 2. Reduction in total energy consumption below that which would have resulted from the adoption of any alternative scheme for melting the additional daily tonnage. 3. Reduction in combustion product volumes, 249 thus allowing waste gas handling systems to be retained and fume control to be improved. 4. Ability of the flame to penetrate slag layers to improve heat transfer to the charge and permit the increased use of lower grade charge materials. Table 4 - Energy Requirements in Copper Reverberatory Furnace With and Without Oxygen Standard Oxygen Practice Practice Charge weight (tonnes) 200 200 Therms/tonne to off bottom 34 26 Oxygen consumption m3/tonne - 40 JAPAN It is only recently that technology-based selling of industrial gases has reached Japan, in areas outside the main steel industry. In common with many countries where this method of selling is introduced, one of the first areas for oxygen use, is in the foundry industry - the cupola. The Japanese were able to take advantage of the experiencffi in the Western World and opted immediately for through-tuyere injection with its associated benefits. The results of two installations have reflected the benefits seen in Europe and USA over the past decade. 1- Melting rate increased by 25% in hot blast cupola. 2. Melting rate increased by 30% in cold blast cupola. 3. Coke consumption reduced by 19% in hot blast. 4. Coke consumption reduced by 24% in cold blast. 5. Equipment cost was low and pay-back periods of three months and six months attained on two installations. 6. Start-up time on the cold blast cupola was cut by 35% from 20 to 14 minutes. Table 5 - Effect of Oxygen on Hot Blast Cupola Before Melting Rate 4t/hr Coke Ratio 13% O 2 Consumption - After 4.8t/hr 11%3 72m /hr |
