The Tizapa Mine is located approximately 130 line kilometers west of Mexico City, the United States of Mexico.
The deposit is classified into strata-bound massive sulfide deposit similar to the Kuroko type deposit in Japan, in which Dowa Mining Co., Ltd. has accumulated much experience and technology for its exploration and development. In fact, the Tizapa Mine is the first example in Mexico developed by+using this technology.
Following the discovery of the deposit by Consejo Recurso de Mineral (CRM) in 1977, exploration was carried out as an Official Development Assistance project between the Mexican and Japanese governments through CRM and Japan International Cooperation Agency/Metal Mining Agency of Japan in 1987. After an international tender offered by Mexican government, the result of the project was succeeded as the development of the Tizapa Mine by Minera Tizapa, S. A. de C. V., a private joint venture company, among Dowa Mining Co., Ltd., Sumitomo Corporation and Industrias Penoles, S. A. de C. V., which is the leading Mexican mining company and the largest silver producer in the world.
The development of the Tizapa Mine has been very successful by mutual cooperation among the parties and now the production is reached at 25, 000 tonnes per month, crude ore. Following the successful result of a surface exploration drilling program around the deposit, an expansion plan aiming at 40, 000 tone per month production is now underway.

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Since Leclanche invented the dry battery with manganese dioxide and zinc as active materials, batteries have yielded revolutionary improvement with the growth of industry. Today, the production of the chemical batteries in Japan has reached 6 billion units, corresponding to 656 billion in sale. Most recent remarkable development of electronic devices has made appliances cordless and small-sized so that high performance batteries have attracted growing interest as small size and high energy density. Nowaday, batteries have been recognized as one of three key devices in electronic industry. We, Mitsui Mining & Smelting Co., Ltd. started the commercial production of electrolytic manganese dioxide in 1949 and has produced variety of key materials for batteries, i. e., zinc alloy powders, lead alloys, cadmium oxide, lithium foils and hydrogen storage alloys. In this paper, high quality of electrolytic manganese dioxide and mercury-free zinc alloy powders will be introduced and Research Development activities for battery materials in Mitsui Mining & Smelting Co., Ltd. will be outlined as well.

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Review of disaster prevention plans is being made everywhere throughout the country after the disaster of the Hanshin Awaji Major Earthquake. Although most of the disaster prevention countermeasures depend on the regional administration, there are very few in stuff having sufficient expertise concerning such countermeasures in local autonomies. Also to promote the projects to build up towns strong enough to be catastropheproof, cooperation of those concerned in the industrical circles or those local dwellers is required. For that purpose, it should be intended that cooperation be secured by the researchers, experts of the business circles, responsible persons of autonomies, etc. who are concerned in variety of the fields such as civil engineering, construction, urban planning, social engineering, etc. as well as earthquake engineering.
In Iwate Prefecture, several researching groups with Iwate University as a pivotal researching medium have gathered reports concerning the ground characteristics and seismic risks in Morioka city area, human consciousness and cry for tsunami disaster countermeasures, in concert with the cities and prefecture. On the other hand, cooperation among the industry world, academic society, and administrative municipalities is intentionally deepened by establishing the research group of ground characteristics and disaster prevention in the Iwate Network System as an information-exchanging agency, in order to actively utilize the fruitful outcomes of the researchs in cooperation.

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Landscape destruction caused by open-cut mining makes an impact on the environmental issue. Landscape evaluation of mined-out quarry becomes necessary from the view point of environmental protection. In this study, we investigated on landscape of mined-out quarry that was reclaimed by revegetating. Three kinds of revegetation, namely herbaceous planting, woody planting and herbaceous + woody planting, were simulated using a color image processing technology with a personal computer. Two psychometrical evaluation tests, rating-scale method and semantic differential method, were conducted using color photomontages as variable stimulus.
In the quantitative analysis by a rating-scale method, it became clear for the landscape reclamation of mined-out quarry that herbaceous planting was better than woody planting when it was seen at a short distance, and woody planting was better than herbaceous planting when it was seen at a long distance. In the factor analysis by a semantic differential method, it became clear that beauty and texture of revegetation were important factors to estimate the landscape evaluation of mined-out quarry.

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The authors are developing a real-time displacement monitoring system by using the Global Positioning System to assess the stability of large slopes. This paper presents the results of field experiments for long-term continuous measurements and discusses the stability and properties of the data obtained by the system. The measured values include random errors, deviations, and largely scattered errors. In order to choose the acceptable data from the original data, including the above errors, a data processing method is proposed in this paper. Applying the proposed method, the system can provide stable and reliable data.
Field experiments for displacement measurements were also conducted to verify the applicability of the system to continuous displacement monitoring. It is concluded that the system can detect at least 5 mm displacements in the horizontal direction and 10 mm displacements in the vertical direction in real time. The accuracy is better than that of the conventional off-line GPS method.

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Based on a self-similar fractal model of JRC profiles, JRC diagram was proposed for a reasonable evaluation of rock joint surface roughness and its size effect. The rock joint surface roughness and its size effect can be evaluated by drawing the fractal model of a rock joint surface profile on the JRC diagram. The fractal model is defined by the steepness and the fractal dimension of the profile. In this paper, variogram method was applied to determine the fractal model and a methodology was proposed to generate the JRC diagram. Moreover, the evaluation method of rock joint surface roughness and its size effect are discussed with considering the interlocking effect of a rock joint.

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A variable-compliance-type constitutive-equation was formerly proposed by Okubo et al. In this brief note, several ways how to obtain a set of four constants required to solve the equation are described. The constant strain-rate test, comparing with creep, constant stress-rate and relaxation tests, is recommended to be most appropriate for obtaining constants readily and easily. Based on some example sets obtained through experimental works on seven Japanese rocks, the effects of confining pressure and moisture content on the value of each constant are discussed.

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In the field of water jet technology the improvement of cutting efficiency has been recognized as one of the most important research targets. To solve this problem an oscillating jet nozzle was developed. In this nozzle several piezo-electric transducers are attached to a vibration plate, and through this plate oscillation of piezoelectric transducers is propagated to inner high pressure water, then oscillating jets emanate from a nozzle outlet.
To optimize the efficiency of the oscillating jet nozzle an appropriate frequency must be selected undergiven water jet velocity and jet diameter.
In this paper the authors examine this problem from the point of hydrodynamic stability of oscillating jets. Firstly the diagram for selecting the optimum oscillation frequency is presented. Then experimental results are compared with theoretical results which were predicted by the hydrodynamic stability theory. Both results show qualitative agreement.

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The depressing effect of raising pulp temperature on pyrite flotation have been investigated by using diethyl dithiophosphate (ethyl aerofloat, E. A. F.) as a collector. The mechanism of depression have been studied in terms of collector adsorption and changes in concentration of sulfate, hydroxide and iron ions in pulp during conditioning, and the surface products after conditioning identified by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) and X-ray photo-electron spectroscopy (XPS).
The results obtained are as follows:
The flotation recovery of pyrite at pH 6 was only slightly decreased by raising pulp temperature from25°C to °C in the presence of large amounts of collector, but it was significantly depressed in moderate collector addition of the order of 200-300 g/t.
There was no difference between collector adsorption at 25 °C and that at 60°C in the collector addition less than 500 g/t. Accordingly, the depression of pyrite by raising pulp temperature can not be explained by the decrease of collector adsorption.
From the changes of the concentration of sulfate, hydroxide and iron ions before and after conditioning at 25°C or 60°C, it was suggested that basic iron sulfate was precipitated on pyrite surface during conditioning at either pulp temperature, but the amount precipitated at 60 t was much larger than that at 25°C, because the oxidation reaction of pyrite surface took place at 60°.
The existence of sulfate on the pyrite surface after conditioning at 60 t was detected by DRIFTS and XPS.
From the above experimental results, it is concluded that pyrite depression by raising pulp temperature is mainly attributed to the formation of hydrophilic basic iron sulfate which offsets the hydrophobization effect with collector adsorption.

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Precious metals are recycled from electric devices. In this study, metallic fragments from shredded mixture were separated using an air table. The air table has a shaking deck motion similar to a wet table and a blast of air is driven through a perforated deck. Several experiments were carried out to demonstrate the effect of frequency, slope angle of the inclined deck and air velocity on separation efficiency. The results indicated that the end slope of inclined deck exerted a great influence of the separation of metallic fragments. The optimum treatment condition was as follows: The angle of slope was 6.5 degrees, frequency of shaking deck was 500 min ^-1, and air velocity were 1.0-2.0 m·Es^-1. The overall separation efficiency at that time was 0.95.

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