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Degradation of rocks and its effect on rock structures
Published in Ömer Aydan, Rock Mechanics and Rock Engineering, 2019
Table 8.1 summarizes some common resulting minerals due to degradation (weathering, oxidation, alteration processes). This subsection presents some of these processes. Feldspars are one of the common rock-forming minerals. Oxidation is the ionic reaction with some components in the original mineral. For example, the oxidation of iron (Fe) results in the hematite mineral: 4 Fe + 3 O2--> 2 Fe2 O3 (hematite) Hydrolysis is a chemical reaction of minerals with water containing dissolved CO2. For example, orthoclase transforms into kaolin as a result of the chemical reaction given by: 2 K Al Si3O6 + 6 H2O + CO2 ---> Al2 Si2 O5 (OH) 4 + 4 H2SiO4 + K2CO3 (orthoclase) (kaolinite) The resulting minerals from the chemical processes are generally clay minerals. It is generally known that dark color minerals are much more vulnerable to degradation compared with whitish or glassy color minerals.
Introduction to Ceramic Fabrication Approaches Including Powder Processing
Published in David W. Richerson, William E. Lee, Modern Ceramic Engineering, 2018
David W. Richerson, William E. Lee
Feldspar is also used in glass, pottery, enamel, and other ceramic products. Feldspar minerals range in composition from KAlSi3O8 to NaAlSi3O8 to CaAl2Si2O8 and act as a flux (reduce the melting temperature) in a composition. Nepheline syenite (Na2Al2Si2O8) is used in a similar fashion.
Minerals
Published in W.S. MacKenzie, A.E. Adams, K.H. Brodie, Rocks and Minerals in Thin Section, 2017
W.S. MacKenzie, A.E. Adams, K.H. Brodie
All feldspars have relatively low relief and low birefringence so that they are recognized by having grey and white interference colours: only near to anorthite composition does a slight yellowish colour appear in a section of standard thickness. Almost all feldspars have two good cleavages and in some sections they appear to be at right angles to one another. In hand specimens, using a lens, the presence of a cleavage serves to distinguish feldspar from quartz since the latter has no cleavage. Most feldspars exhibit twinning and multiple, polysynthetic or lamellar twinning is very common in plagioclase feldspar: in coarse-grained rocks it can often be seen in hand specimen by using a lens.
Environmentally friendly disposal of the full components of gold tailings: feldspar recovery and cemented filling
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Guo-Dong Chen, Xiang-Nan Zhu, Xian-Jun Lyu, Zhi-Ming Wang
As shown in Figure 8, the tailings in the gold ore separation process, or the tailings in the existing tailings dam, are first classified by the hydrocyclone to obtain the coarse-grained fraction and the fine-grained fraction. It is suggested that the classification particle size is 74 μm, which mainly depends on the nature of the ore. For coarse-grained fraction, the iron impurity in the coarse particle is removed by low intensity magnetic separation and high intensity magnetic separation. Then, the flotation method is used to recover the feldspar, and the feldspar concentrate can be used as ceramic raw material. Tailings are used as quartz concentrate. Cemented filling is recommended for the fine-grained fraction, and its concentration is increased by thickener to be more than 56%. The cemented powder is mixed with the concentrated tailings and pumped into the underground goaf.
Manufactured Feldspar-quartz Sand for Glass Industry from Gneiss Quarry Rock Fines Using Dry Rare-earth Magnetic Separation
Published in Mineral Processing and Extractive Metallurgy Review, 2019
Luanna C. Moura, Flávio P. André, Hayla Miceli, Reiner Neumann, Luis Marcelo Tavares
Feldspars are widely used in the glass and ceramic industries. They are used in the production of wall and floor tiles and grès porcelanato porcelain stoneware, besides different types of glasses (Potter 2006; Zhang et al. 2018). Glass manufacture encompasses an enormous range of compositions and product types, for which feldspars act both as fluxing agents and as stabilizers. While fluxes are mainly given by K2O and Na2O, which lower the melting temperature of a glass batch, the stabilizers, given by either Al2O3 or CaO, impart resistance to physical and chemical attacks (Potter 2006). For instance, in the United States, feldspar for clear glass manufacturing is typically finer than either 850 or 425 µm, and contains 4–6% K2O, 4–8% Na2O, approximately 19% Al2O3 and 0.08% Fe2O3 (Potter 2006).
Assessment of Amagunze microcline for alumina recovery in nitric acid and hydrogen peroxide solutions and kinetic study
Published in Canadian Metallurgical Quarterly, 2023
Ikechukwu A. Nnanwube, Okechukwu D. Onukwuli, Ekuma O. Ekumankama
Alumina is found in most places across the world as well as in combination with silica and other minerals. It is found in clays, micas, and feldspars. Alumina is broadly used as a sophisticated ceramic material owing to its blend of chemical, physical and electrical properties. It is also applied in pigments as well as in the production of chemicals. Owing to its exceptional dielectric and insulating properties, there is high demand for alumina from the electrical and electronic sectors. Over 90% purity is required for alumina to be deployed for high technical applications. It is also required to have low contents of sodium and iron [2]. The Bayer’s process which uses bauxite, an acidic ore, as its raw material is the major route through which aluminium and its chemicals are produced through alkali leaching [3]. More than 90% of alumina is produced through the Bayer process globally, with Bayer bauxite residue accounting for a very large percentage of the byproducts of alumina extraction. The alkaline materials found in Bayer bauxite residue comprises not only soluble Na2CO3, NaOH, Na2SiO3 and, NaAlO2, left over from the solution phase, but also a zeolite sodium alumino-silicate hydrate (Na2O.Al2O3.xSiO2.mH2O) as well as metastable, amorphous non-soluble alkaline substance [4,5] generated from the reaction between the bauxite and strong alkaline solution [6,7]. These waste products are generally difficult and expensive to handle and can also contaminate the air, soil, and water, posing serious danger to the ecosystem [8].