Japanese cement industry has been utilizing many kinds and quantity of waste and by-product to substitute raw materials and fuel. The total amount of the waste utilized in Japanese cement industry reached 28 million tons in 2001, which is equivalent to 355 kg of waste utilization for one ton of cement production.
As the chemical composition of waste is very similar to the clay, which is one of the cement raw materials such as limestone, clay, iron ore, etc., most of the waste is utilized as a substitute of clay.
The noticeable point of using waste in the cement industry is that all of the waste fed in the cement manufacturing process is turned to the cement and no waste is generated from the process. Moreover, as the materials fed in the system pass through the high temperature zone of as high as 1450 degree C, all of the hazardous compounds are discomposed inside of the process.
In conclusion, it is said that cement industry has advantageous features for the disposal of waste.

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Evaluation of crack extension in the stress relief process is successfully performed, using a new index called the Ratio of Crack Opening Dependency (RCOD), that is theoretically in inverse proportion to the normalized Young's modulus of rock mass, and by applying the fracture mechanics. Cracks with stress relieving are classified into the primary crack of microscopic, which plays an important role for determining the effective Young's modulus in the first stage of stress relief, and the secondary crack of macroscopic, the excessive propagation of which results in forming of plate structure within rock mass and subsequent the strength failure and strain softening of rock mass. The present paper focuses on the evaluation of the secondary crack extension by means of RCOD. Theory and practice of quantitative crack evaluation is demonstrated, along with the analysis of the field data obtained in the construction of two underground power houses. Subsequently the application of fracture mechanics is discussed to forecast the secondary crack extension, along with case examples. The increase of rock strain with the secondary crack extension is successfully forecasted, using the intensity factor and the normalized compliance of the homogenized multi-crack model in an alternative arrangement.

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Oxygen probes were applied to a PS converter in copper-making operation, and the oxygen pressures of white metal and blister copper in the converter were measured through the converter's mouth and through a tuyere, respectively. Based on the obtained results, the following reaction mechanism has been deduced.
(1) The copper-making stage of a PS converter may be classified into three stages, i.e. the early substage where the tuyeres are completely in white metal, the intermediate substage where both phases of white metal and blister copper coexist in the converter and the tuyeres are in the blister copper, and the final substage where the white metal has disappeared from the converter.
(2) In the early stage, direct oxidation of white metal by oxygen gas contained in the reaction air progresses in the vicinity of the tuyeres.
Cu₂S(l) + O₂(g) = 2Cu(l) + SO₂(g) …………… (1)
(3) In the intermediate substage, the following three reactions proceed near the tuyeres, at the interface of blister copper and white metal phases, and in the bulk of the blister copper, respectively.
O₂(g) = 2O(l) …………… (2)
Cu₂S(l) = 2Cu(l) + S(l) …………… (3)
S(l) + 2O(l) = SO₂(g) …………… (4)
Here the most important factor is that reaction(4) progresses under the condition of P_SO2=1atm. It is not dependent on how high the SO₂ pressure of the waste gas from the converter is. Because the condense phases, i.e. the white metal and blister copper phases, are not in equilibrium with the gas phase.
(4) In the final substage, reactions(2) and (4) only proceed because the white metal is no longer in the converter. Some of the blister copper can be excessively oxidized to the extent that Cu₂O(s) is formed according to equation(5). However the final degree of oxidation of the whole blister copper does not reach this level.
2Cu(l) + 1 / 2 O₂(g) = Cu₂O(s) …………… (5)

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Microbially mediated dissolution of arsenopyrite by Acidithiobacillus ferrooxidans and its suppression by two kinds of organic matters was investigated. Results are summarized as follows:
(1) In the microbially mediated dissolution of arsenopyrite by Acidithiobacillus ferrooxidans, the dissolved arsenic species inhibited the growth and activity of the microorganism, therefore, the dissolution rate was slow in comparison with those of pyrite.
(2) In the presence of low concentrations of tannic acid, the growth and activity of the A. ferrooxidans were not inhibited but accelerated.
(3) The presence of extractant after autoclaving Acacia Mangium, which contains trace amounts of poly-phenolic derivatives, leads the fast consumption of oxygen and strongly reducing function, therefore, quickly inhibited the first oxidation of arsenopyrite by oxygen. It is fairly different from the suppression mechanism by tannic acid.

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According to an official report, the annual total discharge of the sewage sludge in Japan shows a tendency to increase in more than 72 million tons in 1998. An efficient utilization technique should be developed to facilitate decreasing of sewage sludge, because the landfill cannot be accepted for the industrial waste any more.
The purpose of this paper is to renovate the conventional treatment of the sludge with the decrease of the environmental impact, adding the convenience of the application and handling to it. An solidification technology was developed for making carbonized tablets from the sewage sludge through mixing the malt feed and zeolite as additive.
Moreover, the thermal properties of the carbonized sludge, which was dependent on the temperature and the time of carbonization of it, were evaluated with thermal analyzers such as TG (thermogravimetry), DTA (differential thermal analysis), DSC (differential scanning calorimetry), and calorimeter.
It was confirmed that the carbonized tablets had the high quantity as biomass, when they were produced at the lower temperature of 300 °C for 25 minutes to 75 minutes. The analytical results with calorimeter indicated that the heating value of the tablets were about 3,800 cal which was corresponded to nearly 60 % of the one of charcoal.
The carbonized tablets made from the sewage sludge can be expected to make application as a fuel in the heating systems of greenhouses, factories, and households.

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Silica recovered from Sumikawa geothermal brines by reaction with cationic precipitant was examined to the industrial application as admixtures to high strength cements. The silica deposits from brines consist of > 90 % silica and H₂O with minor amounts of Al, Ca and Na. They were converted to silica fume (spherules of 1 to 10 m in diameter) by heating at 180°C in a spray-dryer. Then, the products were heated up to 900°C and sintered in an oven for 2 hours. During this process, the zeta potentials of the products drastically changed from positive to negative values at 300°C in calcination temperature. The sintered products were mixed with cement and the strength of the hardened body exceeds > 100 N/mm². These results show that the fumed silica converted from excess silica in geothermal brines can be applied as admixtures to high strength cements.

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Life cycle inventory analyses for Pb solder and Pb-free solder in printed wiring boards (PWBs) were conducted to evaluate CO₂ emissions during the life cycles of the solders. We assumed that both Pb solder and Pb-free solder were to be either defused by solidification or recycled at the end of their lives. We found that in the life cycles of both solders, the predominant CO₂ emissions occurred during the mounting process and waste treatment. In the case of Pb solder, the detoxification process during the waste treatment consumed a large amount of energy; this was avoided by recycling the Pb solder, leading to a reduction in the total life cycle CO₂ emissions. The life cycle CO₂ emissions for Pb solder were 125 kg-CO₂ / Sn-Pb eq. kg in the case where 100% of the Pb solder was recycled at the end of its life. On the other hand, the life cycle CO₂ emissions for Pb-free solder were independent of the recycling ratio and were approximately 112 kg-CO₂ / Sn-Pb eq. kg. We also investigated how separating the phenol resin from the PWBs during the recycling process affected the life cycle CO₂ emissions for the solders. We found that separating phenol resin from waste PWBs could contribute to the reduction of CO₂ emissions during the recycling process, but not to the overall reduction of life cycle CO₂ emissions for the solders.

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