In order to seize the operational problems and clarify the various phenomena in a blast furnace operated at the extremely low fuel rate, Nippon Kokan K. K. had decided to execute a trial operation in No. 3 blast furnace (inner volume : 3 223 m3, blow in; Jan. 1975) at Fukuyama works.As a result, a monthly mean fuel rate of 396 kg/t was recorded in Nov. 1981. Comparing with the previous result of the same furnace (428 kg/t, Jan. 1979), necessary heat at the lower part of a furnace could be much reduced. Both the high reducibility of sinter and adequite burden distribution control enabled to maintain the high shaft gas efficiency of 97.5%. As the heat flux ratio increasing, temperature level at the shaft lowered and the three stages of thermal reserve zones were observed. The level of cohesive zone also lowered and its shape changed from "inverse V" to "V" bia "W" shape, furthermore some of measured results indicated that melting line would be very close to the raceway. In its transition period, burden desending became a little unstable, but got well again when fuel rate reduced to around 400 kg/t.The essential hindrances to get further low fuel rate in future are seemed to be the reducibility of are at the short effective zone for its reduction and the fusing capacity of ore around the raceway.

Denitrification of paddy fields is a key process for improving water quality in fields where nitrate concentrations are high. The objective of the present study was to understand the effects of incorporating organic carbon (C) into soil on the denitrification rate of paddy fields in winter. On 11 December 2007, separate paddy field plots were prepared by incorporating 5 Mg ha )1 of rice straw (RS), 11 Mg ha )1 of rice straw compost (RSC) or a control. A field with a high concentration of nitrate in the water (averaging 18 mg N L )1 ) was irrigated until 29 March. During the experiment, the daily average soil temperature at a depth of 0.05 m ranged between 3 and 15°C. The nitrate concentration in the surface water in the RS plot, where the residence time was 2 days, decreased more than the concentration in the control or RSC plots. The total estimated nitrate removal from each plot in relation to the other plots was RS > RSC = control. Measurements of the soil from each plot on 29 February 2008 showed that incorporation of RS significantly increased the denitrification potential, even at low temperatures (5-10°C). Furthermore, the RS plot contained more dissolved organic C than the control or RSC plots. This result indicates that supplying RS effectively increases denitrification under low-temperature conditions.

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Synopsis In order to clarify the various phenomena in a blast furnace and its operational problems at the extremely low fuel rate, Nippon Kokan K.K. decided to execute a trial operation in No. 3 blast furnace (inner volume: 3 223 m3, blow in; January 1975) at Fukuyama Works. As a result, a monthly mean fuel rate of 396 kg/ T was recorded in November 1981. Comparing with the result of the previous test operation in the same furnace (428 kg/ I, January 1979), heat requirements at the lower part of the furnace could be much reduced. Both the high reducibility of sinter and adequate burden distribution control enabled to produce and keep the high shaft gas efficiency of 97.5%. As the heat flux ratio increased, temperature level at the shaft lowered and the three stages of thermal reserve zones were observed. The level o f cohesive zone also lowered and its shape changed from " inverse V " to " V " via " W " shape, furthermore some of the measured results indicated that the melting line would be very close to the raceway. In its transitional period, the burden descent became somewhat unstable, but got well again when the fuel rate reduced to around 400 kg/T.