text: The following advantages have been reported for the BBOC:
  * very high oxygen efficiency – the injection of oxygen directly into the reaction zone within the furnace results in much greater oxygen efficiency (close to 100%) than with reverberatory furnaces (8% for the Niihama furnace) or top-blown rotary converters (about 30%)
  * reduced off-gas volume – the use of industrial oxygen and the high oxygen efficiency of the process means that excess air is not required to achieve the results. This reduces the off-gas volume and thus the cost of the off-gas train and handling equipment. Rand Refinery reported that the off-gas volume of the BBOC was about 75% of that of a TBRC with a special lance conversion and only 19% of that of top-submerged lance smelting. Niihama refinery reported that its BBOC had 15% of the off-gas volume of its reverberatory furnace while producing 1.8 times the product
  * higher reaction rates – by injecting the oxygen directly into the reaction zone, the reaction rates are much higher than in reverberatory furnaces where the oxygen has first to penetrate the slag layer. BRM reported a reaction rate per unit of furnace volume of 10–20 times that of the reverberatory furnace
  * lower refractory wear – Rand Refinery reported that the refractory linings of its TBRC furnaces needed replacing after approximately two weeks, while the linings of its BBOC furnace lasted about 14 weeks
  * lower precious metal inventories – a consequence of the higher reaction rates is that smaller furnace volumes are required and there are smaller cycle times. This results in lower precious metal inventories. In lead slimes bullion processing, the silver inventory was reduced from 4.5 t to 1.25 t after replacing a reverberatory furnace with a BBOC and at BRM the silver inventory fell from 11.5 t to 3.1 t with the introduction of the BBOC furnace
  * better energy efficiency – a supplementary burner is needed only during heating the charge and doré casting operations. During cupellation, the oxidation reactions provide sufficient heat to maintain temperature. There was a 92% reduction in fuel consumption per tonne of doré treated reported for the BBOC at the Niihama refinery
  * better product quality – BHAS reported that lead and copper levels in silver produced from the BBOC of 0.01% and 0.1% respectively were possible when the furnace was operating under design conditions, compared to 0.04% and 0.2% for the old reverberatory furnace, and 0.8% and 0.4% for the Sirosmelt furnace. Rand Refinery reported that a doré bullion of 99.2% was achievable. BRM reported that its doré is 99.7% silver
  * higher recoveries of precious metals – due to changes in the way the BBOC is operated compare to reverberatory furnaces, notably in being able to use deeper layers of slag, there is an increase in the recovery of precious metals compared to the reverberatory furnaces. Replacement of reverberatory furnaces with BBOC furnaces saw the direct silver recovery increase from 92.5% to 97.5% at BRM and from 70% to over 95% at Niihama
  * simple vessel design – the BBOC has a relatively simple vessel design, without the complex moving parts of TBRCs
  * good process control – the high oxygen utilization allows good process control, particularly when combined with an oxygen sensor in the off-gas system
  * lower labor requirements – the BBOC has a lower labor requirement than reverberatory furnaces, top-submerged lance furnaces and TBRCs
  * lower operating costs – lower labor requirements, lower fuel requirements and longer refractory life contributed to a 28.3% reduction in overall operating costs when the BBOC was installed at the Rand Refinery
  * lower capital cost – the BBOC is a simpler furnace than TBRC or top-submerged lance furnaces. Rand Refinery reported a capital cost comparison indicating that its BBOC option was 67% of the cost of a top-submerged lance option.