Mechanical Properties of New Ceramic Materials Obtained from Granular Solid Residuals Coming from Mines and Diatomaceous Earth

Abstract

Granular solid residuals are produced by different industries in Mexico. Some of these are considered dangerous because they are stored in open areas contaminating and affecting the flora, fauna, and aquifers, and occasionally to the human being. These solid residuals coming from mines and diatomaceous earth are known as “jales” (nahualt derivated from xalli, it means sand). The “jales” have a high content of cyanide and heavy metals. These high contents are commonly out of the limits permitted by the Mexican standards. On the other hand, the “diatomita” (diatomaceous earth) is not as dangerous as the “jales”, however, this needs a treatment to eliminate the occluded organic material. This is normally used by producers of gelatin, antibiotics, industrial grease and oil, sugar refining, etc. The leaching process of metals using the sodium cyanide was introduced in 1887 (Li, 1993). This revolutionizes the techniques to obtain gold and silver. This is a method usually employed in the world to recover metals. Two international patents were obtained by developing equipment and also a process to extract toxic metals and wastes from foundry sands (Vite, 1994a, 1994b). In addition, a national patent was achieved by the leaching of heavy metals from foundry sands (Vite, 1997). Approximately, 330,000 tons of these solid residuals are generated daily in Mexico. In some states, such as Guanajuato, Zacatecas and cities as Pachuca in the state of Hidalgo, the waste deposits are found in open areas. The chemical composition of these solid residuals is varied. Figure 1 shows a photograph of the pipe used to transport the solid residuals until a “jales” dam. An important case is related to “jales” when they have high pyrite content (FeS2). This affects considerably the chemical composition due to their weathering. Due to this fact, it is necessary to process the “jales” before being used at applications such as the construction of landfills in the leveling of roads, additives for asphalt mixtures or dam construction (Botz & Stevenson, 1995, Orozco & Orozco, 1992, Sengupta, 1993, Vite et al., 2003, Wills, 1994).