Calcium Carbonate

The Calcium Carbonate Project is a planned processing factory project, to be located in the Yanbu Industrial City, Province of Madinah, Kingdom of Saudi Arabia. Yanbu is in the west of Saudi Arabia, on the Red Sea Coast, about 400km north of Jeddah. The factory processes marble and limestone mined and initially processed by UMIC from several different deposits. The raw material for calcium carbonate rock is widespread and can be found dissolved in rivers and oceans up to being a major constituent of mountain ranges.

A sedimentary rock wholly or mostly comprised of calcium carbonate is called Limestone. When poorly compacted, the rock is called Chalk. If magnesium is present during the sedimentation process, a mixed calcium/magnesium carbonate may occur, called Dolomite. Under conditions of high pressure and temperature, limestone can undergo a recrystallisation process. The resulting rock is called Marble, a metamorphic rock.

Preliminary field exploration work, mapping, sampling and drilling were undertaken on the deposits. The samples were subjected to laboratory and mechanical testing. These studies were carried out in collaboration with the Saudi Geological Survey (SGS) and international consultants. The results were utilised to prepare a feasibility study, which included mine planning, factory design and recommended output products.

The factory produces two different types of calcium carbonate:

Ground Calcium Carbonate (GCC)

Two processes are used to produce GCC:
  • A dry process line, where a series of crushing and fine milling stages produces a fine (micronised) product. During the processing, the material is beneficiated, to improve the colour of the products. The size of the process input is 24 mm, or less and the size of the standard output product is 5 microns (0.005 mm). Generally, the product will be packed into 50 kg bags.
  • A wet process line, which initially uses a similar process to that described above. The material is then beneficiated using a froth flotation process to removing impurities such as silica and carbonaceous matter. The beneficiated calcium carbonate is then filtered and dried, followed by a fine milling to the required size.

Precipitated Calcium Carbonate (PCC)

Is produced by a separate wet process that includes the following stages:

Calcination (heating) of the raw material to 900 degrees Celsius, using natural gas as the fuel. Calcination causes the calcium carbonate contained in the raw material to decompose calcium oxide (lime) and carbon dioxide [CaCO3 => CaO + CO2].

The produced lime is then slaked in water, to produce calcium hydroxide (quicklime) [ CaO + H2O => Ca(OH)2].

The produced slaked lime then carbonated to precipitate Calcium Carbonate [Ca(OH)2 + CO2 => CaCO3 + H2O].

The precipitated calcium carbonate (PCC), which is free of impurities, is then filtered in a belt filter followed by drying in a flash dryer.

The dried calcium carbonate is then fine milled to the required particle size.

PCC is used in cosmetics, as a filler in dentistry and other industries requiring pure, fine filler.