KELLA SILICA SAND

Newera was granted mining license for silica sand in the Southern Nations and Nationalities Regional State, Gurage Zone, Sodo Woreda, Kella locality. The license area is located c. 110km south of Addis Ababa and covers a total area of 1.42 sq. km.

The license area lies within the central part of the Ethiopian Volcanic Province. This volcanic province is situated at the contact between western Ethiopian Plateau and western margin of central and northern Main Ethiopian Rift (MER). The regional geology of the area can be traced from Precambrian to the Recent: Precambrian gneiss, Mesozoic sediments, Paleogene (Late Eocene-Late Oli-gocene) fissural flood basalts with minor rhyolite, trachyte and pyroclastic flows, Neogene (Miocene – Pliocene) pyroclatic, rhyolite and trachytic flows with minor salic flows, and Pleistocene – Holocene basic to felsic volcanics and phreatomagmatic deposits intercalated with lacustrine and alluvial deposits.

Resource estimation of the sandstone unit showed that a total of 91.9million tons of sandstone unit is estimated in the license area. Of the total resource estimated, only 24.8million tons of the sandstone unit can be mineable at the current economic situations. Thus, NMP has planned to setup a silica sand crusher and washing plants that can process up to 225,000t of silica sand per annum to supply the emerging glass manufacturing industry and also export the product to the Asian market.

 

Use of Silica Sand

 

Glass Making

Silica sand is the primary component of all types of standard and specialty glass. It provides the essential SiO2 component of glass formulation and its chemical purity is the primary determinant of color, clarity and strength. Industrial sand is used to produce flat glass for building and automotive use, container glass for foods and beverages, and tableware. In its pulverized form, ground silica is required for production of fiberglass insulation  and  reinforcing  glass fibers. Specialty glass applications include test tubes and other scientific tools, incandescent and fluorescent lamps, television and computer CRT monitors.

Metal Casting

Industrial sand is an essential part of the ferrous and non-ferrous foundry industry. Metal parts ranging from engine blocks to sink faucets are cast in a sand and clay mold to produce the external shape, and a resin bonded core that creates the desired internal shape. Silica’s high fusion point (1760°C) and low rate of thermal expansion produce stable cores and molds compatible with all pouring temperatures and alloy systems. Its chemical purity also helps prevent interaction with catalysts or curing rate of chemical binders. Following the casting process, core sand can be thermally or mechanically recycled to produce new cores or molds.

Metal Production

Industrial sand plays a critical role in the pro- duction of a wide variety of ferrous and non- ferrous metals. In metal production, silica sand operates as a flux to lower the melting point and viscosity of the slags to make them more reactive and efficient. Lump silica is used either alone or in conjunction with lime to achieve the desired base/acid ratio required for purification. These base metals can be further refined and modified with other ingredients to achieve specific properties such as high strength, corrosion resistance or electrical conductivity. Ferroalloys are essential to specialty steel production, and industrial sand is used by the steel and foundry industries for deoxidation and grain refinement.

Chemical production

Silicon-based chemicals are the foundation of thousands of everyday applications ranging from food processing to soap and dye production. In this case, SiO2 is reduced to silicon metal by coke in an arc furnace, to produce the Si precursor of other chemical processes. Industrial sand is the main component in chemicals such as sodium silicate, silicon tetrachloride and silicon gels. These chemicals are used in products like household and industrial cleaners, to manufacture fiber optics and to remove impurities from cooking oil and brewed beverages.

 

Construction

Industrial sand is the primary structural component in a wide variety of building and construction products. Whole grain silica is put to use in flooring compounds, mortars, specialty cements, stucco, roofing shingles, skid resistant surfaces and asphalt mixtures to provide packing density and flexural strength without adversely affecting the chemical properties of the binding system. Ground silica performs as a functional extender to add durability and anti-corrosion and weathering properties in epoxy based compounds, sealants and caulks.

Filtration and Water Production

Industrial sand is used in the filtration of drinking water, the processing of waste water and the production of water from wells. Uniform grain shapes and grain size distributions produce efficient filtration bed operation in removal of contaminants in both potable water and wastewater. Chemically inert, silicawil11 not degrade or react when it comes in contact with acids, contaminants, volatile organics or solvents. Silica gravel is used as packing material in deep water wells to increase yield from the aquifer by expanding the permeable zone around the well screen and preventing the infiltration of fine particles from the formation.

Ceramics and Refractories

Ground silica is an essential component of the glaze and body formulations of all types of ceramic products, including tableware, sanitary ware and floor and wall tile. In the ceramic body, silica is the skeletal structure upon which clays and flux components attach. The SiO2 contribution is used to modify thermal expansion, regulate drying and shrinkage, and improve structural integrity and appearance. Silica products are also used as the primary aggregate in both shape and monolithic type refractories to provide high temperature resistance to acidic attack in industrial furnaces. In Deep water wells to increase yield from the aquifer by expanding the permeable zone around the well screen and preventing the infiltration of fine particles from the formation.

 

Recreational Products

Industrial sand even finds its way into sports and recreation. Silica sand is used for golf course bunkers and greens as well as the construction of natural or synthetic athletic fields. In golf and sports turf applications silica sand is the structural component of an inert, uncontaminated, growing media. Silica sand is also used to repair greens and to facilitate everyday maintenance like root aeration and fertilization. The natural grain shape and controlled particle size distribution of silica provides the required permeability and compaction properties for drainage, healthy plant growth and stability.