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2. Na 2 CO 3 + Ca(OH) 2 ←→ 2 NaOH + CaCO 3. Calcium carbonate precipitates from the white liquor and is recovered and heated in a lime kiln where it is converted to calcium oxide (lime). 3. CaCO 3 → CaO + CO 2. Calcium oxide (lime) is reacted with water to regenerate the calcium hydroxide used in Reaction 2: 4. CaO + H 2 O → Ca(OH) 2
The construction industry is the number one user of phosphogypsum in 2020, with 10.5 Mt used as concrete set retarder and 3.5 Mt used in drywall. [13] It is also used as a chemical feedstock for producing sulfates, and as a soil conditioner similar to regular gypsum. [14]
Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO 4 and related hydrates. In the form of γ- anhydrite (the anhydrous form), it is used as a desiccant . One particular hydrate is better known as plaster of Paris , and another occurs naturally as the mineral gypsum .
The finishing transformation that takes place in the hottest part of the kiln, under the flame, is the reaction of belite (C 2 S = 2CaO·SiO 2, or Ca 2 SiO 4) with calcium oxide to form alite (C 3 S = 3CaO·SiO 2, or Ca 3 SiO 5): Ca 2 SiO 4 + CaO → Ca 3 SiO 5. Also abbreviated in the cement chemist notation (CCN) as:
Chemical pulping involves dissolving lignin in order to extract the cellulose from the wood fiber. The different processes of chemical pulping include the Kraft process, which uses caustic soda and sodium sulfide and is the most common; alternatively, the use of sulfurous acid is known as the sulfite process, the neutral sulfite semichemical is treated as a third process separate from sulfite ...
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The calcium cycle is a transfer of calcium between dissolved and solid phases. There is a continuous supply of calcium ions into waterways from rocks, organisms, and soils. [1] [2] Calcium ions are consumed and removed from aqueous environments as they react to form insoluble structures such as calcium carbonate and calcium silicate, [1] [3] which can deposit to form sediments or the ...
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk.