Use of pumice stone as a ceramic raw material

Pumice stone is a highly porous volcanic mineral. its porous structure is due to the expansion during cooling steam and gases contained in the molten lava. Pumice is a low cost industrial mineral found near some volcanic mountains in solid blocks, fragments, or in mixtures of fines and coarse pieces. In the world, high quality large pumice reserves can be found in a number of countries in large quantities. It is a glassy silicate mineral with varying composition. SiO2 is the major component of the mineral. In addition to SiO2, it contains several other metal oxides in various ratios. In composition, it resembles the raw materials of most ceramic products. All these, the ease of availability, composition and low price, make pumice a potential ceramic raw material. In this study, the potential for use of pumice as a ceramic raw material was investigated. Also presented are the experimental results obtained using pumice samples from Kayseri, Turkey

Production of low-density ceramics using pumice stone

Pumice stone is a porous silicate mineral of volcanic origin. Pumice offers some unique characteristics such as low cost, strength, and occurrence in various compositions and colors. Its 3 most attractive property for many applications is its low density, which can be as low as 0.4 g/cm(3). The most of the pumice produced today is consumed by construction industries, while smaller amounts are used in several other areas varying from production of cleansers, polishes and chemicals to soil remediation. Its chemical composition, when combined with other properties like low cost and low density, makes it a good candidate as a potential raw material in the production special ceramics. For example, partial sintering of the mineral gains will reduce the density of products due to the porous structure still remaining inside. Although this porous structure will reduce the strength to some extent, it will result in a ceramic product with some attractive properties such as low density and low conductivity for heath and sound. This presentation covers an experimental investigation to produce low-density ceramic products using pumice as the main raw material. The studied parameters include the effects of the composition, grain size, temperature, degree of sintering, and types and ratios of binders on the properties of products

Alternatives to cyanide in the gold mining industry: what prospects for the future

This paper reviews a series of alternative lixiviant systems for the recovery of gold from ores and concentrates. For over 100 years, cyanide has been the leach reagent of choice in gold mining because of its high gold recoveries, robustness and relatively low costs. The environmental damages resulting from its mismanagement, however, have initiated widespread research aimed at identifying and developing less toxic leaching agents. The most widely-researched alternative lixiviants for gold ores are examined in this paper, but it is evident that none has yet made any significant inroad into the dominant position of cyanide as the reagent of choice at the vast majority of gold mines worldwide. (c) 2005 Published by Elsevier Ltd