1305-78-8 Usage
Description
Calcium oxide, also known as lime, quicklime, burnt lime, or calx, is an odorless, white or gray-white solid in the form of hard lumps. It is a strong irritant to skin, eyes, and mucous membranes. Calcium oxide is produced from calcium carbonate, limestone, or oyster shells by calcination at high temperatures. It is a caustic crystalline alkali substance with a very high affinity for water, reacting exothermically to form calcium hydroxide.
Uses
1. Used in Chemical Industry:
Calcium oxide is used as an analysis reagent and flux agent for manufacturing fluorescence powder. It is also used as an inexpensive alkali in the chemical industry and is widely used in pesticides, paper, food, petrochemical, and leather industries.
2. Used in Metallurgy:
Calcium oxide is used in the manufacture of calcium carbide, soda ash, and bleaching powder. It is also used as a metallurgical flux agent and for the removal of impurities during the refining of iron ore.
3. Used in Construction:
Calcium oxide is used as a building material, particularly in the production of bricks, plaster, mortar, stucco, and other construction materials. It is also used in the production of Portland cement, which is the basis for most mortars and concrete.
4. Used in Agriculture:
Calcium oxide is used as a soil conditioner and calcium fertilizer. It has a high neutralizing value and is used to neutralize acidic soils, improving soil structure and fertility.
5. Used in Water Treatment:
Calcium oxide is used in water and sewage treatment, as well as in the purification of metal refining processes. It is also used in the remediation of mine wastes to recover cyanides and neutralize acid mine drainage.
6. Used in Food Industry:
Calcium oxide is used as an anticaking agent, firming agent, and nutritive supplement in applications such as grain products and soft candy.
7. Used in Laboratory:
Calcium oxide is used for the drying of laboratory ammonia and alcohol dehydration.
8. Used in Drug Delivery Systems:
Calcium oxide can be used as drug carriers, enhancing the delivery, bioavailability, and therapeutic outcomes of various pharmaceuticals.
9. Used in Flotation of Minerals:
Lime, or calcium oxide, is the most widely used reagent in the mineral industry for the flotation of sulfides and, in some cases, non-sulfide minerals.
10. Used in Glass Manufacturing:
Calcium oxide is the principal flux in medium and high-temperature glazes, beginning its action within the glaze around 1100°C. It must be used with care in high-fire bodies due to its active fluxing action.
Content analysis
Approximately 1 g of the sample was burned to constant weight (accurately weighed) and dissolved in 20 ml of dilute hydrochloric acid solution (TS-117). After cooling, dilute to 500.0ml with water and mix uniformly. Take 50 mL of this solution into the appropriate container, add 50ml of water. Add 30 mL 0.05ml/L disodium EDTA via a 50 mL burette with stirring (preferably with a magnetic stirrer); further add 15ml sodium hydroxide solution (TS-224) and hydroxy naphthol blue indicator (300 mg) for continue titration to the blue end. Per ml of 0.05 mol/L of EDTA corresponds to 2.804 mg of calcium oxide.
Identification test
1 g of the sample was shaken with 20 ml of water, and the acetic acid test solution (TS-1) was added to dissolve the sample. The calcium test (IT-10) of this solution was positive.
Toxicity
ADI is not subject to restrictive regulations (FAO/WHO, 2001).
GRAS (FDA, §18.5210; §184.12l0, 2000);
See Calcium Oxide.
It can stimulate the mucous membrane, causing sneezing, in particular, can cause fat saponification so the water will be absorbed by the skin, dissolving the protein with stimulating and corroding the tissue. It has strong effect against the eye mucosa, being able cause oral and nasal mucosa superficial ulcers, and sometimes there may be perforation of the nasopharyngeal diaphragm, deep respiratory tract disease. Inhalation of lime dust may cause pneumonia.
In case of inhalation of dust, it can be treated via inhaling water vapor (add some of the citric acid crystals to the water in advance) and coat the mustard cream in the chest. If falling into the eyes, we can open up the eyes and immediately rinse with running water for 10~30 min and then rinse with 5% ammonium chloride solution. When the skin burns, it can be used with 5% citric acid, tartaric acid, acetic acid or salt solution of mineral oil or vegetable oil to remove the lime residue sticking to the skin.
The maximum allowable concentration in the United States is 5 mg/m3.
During operation, it should be paid attention to the protection of respiratory organs. Wear uniforms manufactured using dust-proof fiber, gloves and closed dust-proof glasses. Coat the ointment-containing grease. Clean after work. During the preparation and application, it should be prevented of dust inhalation.
Production method
Calcium carbonate calcination first apply calcium carbonate for reaction with hydrochloric acid to generate calcium chloride, followed by addition of ammonia for neutralization, standing for precipitation and filtration, followed by adding sodium bicarbonate for reaction to generate calcium carbonate precipitate. It is further subject to centrifugal separation dehydration, drying and calcination, followed by crushing and screening to obtain the finished product of medicinal calcium oxide. Its reaction is:
CaCO3 + 2HCl → CaCl2 + CO2 + H2O
CaCl2 + 2NH3? H2O? Ca (OH) 2 + 2NH4Cl
Ca (OH) 2 + NaHCO3 → CaCO3 + NaOH + H2O
CaCO3 [△]→CaO + CO2 ?.
Limestone calcination method: crush the coarse limestone to 150 mm, and screen for the fine residue below 30 to 50 mm. Anthracite or coke required a particle size to be below 50 mm, which contains not too much low melting point ash content. The amount of anthracite or coke is 7.5% to 8.5% of that of limestone by weight. The selected limestone and fuel are timely and quantitatively supplied from the kiln crown to the kiln, further calcinated at 900~1200 ℃ and then lead to the finished product after cooling. In the calcination process, carbon dioxide is produced as by-product. Its reaction equation is:
CaCO3 [△]→CaO + CO2 .
Usage limitation
GB 14880-94 (in terms of Ca, g/kg): beverages, cereals and their products, 1.6~3.2; infant food, 3.0~6.0.
GB 2760-2001: Preparation of water 100mg/L (36mg/L in terms of Ca).
Hazards & Safety Information
Category Corrosive items
Toxic classification poisoning
Acute toxicity Intraperitoneal-mouse LD50: 3059 mg/kg
Explosive and hazardous properties it is corrosive to the skin; powdered calcium oxide can be mixed with water to be explode; its mixture with alcohol can be flammable and explosive upon heating
Flammable hazardous characteristics exothermic upon water with its heat being able to cause organic combustion; one of the air pollutants with heating together with alcohol mixture being able to cause combustion
Storage and transportation characteristics Treasury: Ventilated, low temperature and drying; Store separately from combustible materials, acids and phosphorus pentoxide.
Fire extinguishing agent mist water, sand
Occupational Standard TLV-TWA 2 mg/m3; STEL 5 mg/m3
History
Calcium oxide dates from prehistoric times. It is produced by heating limestone to drive off carbon dioxide in a process called calcination: CaCO3(s) CaO(s) + CO2(g). At temperatures of several hundred degrees Celsius, the reaction is reversible and calcium oxide will react with atmospheric carbon dioxide to produce calcium carbonate. Efficient calcium oxide production is favored at temperatures in excess of 1,000°C. In prehistoric times limestone was heated in open fires to produce lime. Over time, lined pits and kilns were used to produce lime. Brick lime kilns were extensively built starting in the 17th century and the technology to produce lime has remained relatively constant since then.
Production Methods
Calcium oxide is commercially obtained from limestone. The carbonate is roasted in a shaft or rotary kiln at temperatures below 1,200°C until all CO2 is driven off. The compound is obtained as either technical, refractory or agri cultural grade product. The commercial product usually contains 90 to 95% free CaO. The impurities are mostly calcium carbonate, magnesium carbon ate, magnesium oxide, iron oxide and aluminum oxide.
Air & Water Reactions
Crumbles on exposure to moist air. Reacts with water to form corrosive calcium hydroxide, with evolution of much heat. Temperatures as high as 800° C have been reached with addition of water (moisture in air or soil). The heat of this reaction has caused ignition of neighboring quantities of sulfur, gunpowder, wood, and straw [Mellor 3: 673 1946-47].
Reactivity Profile
A base and an oxidizing agent. Neutralizes acids with generation of heat. Nonflammable, but will support combustion by liberation of oxygen, especially in the presence of organic materials. Reacts very violently with liquid hydrofluoric acid [Mellor 2, Supp. 1:129 1956]. Reacts extremely violently with phosphorus pentaoxide when reaction is initiated by local heating [Mellor 8 Supp.3:406 1971].
Hazard
Evolves heat on exposure to water. Danger-
ous near organic materials. Upper respiratory tract
irritant.
Health Hazard
Causes burns on mucous membrane and skin. Inhalation of dust causes sneezing.
Fire Hazard
Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars etc.). Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.
Flammability and Explosibility
Notclassified
Safety Profile
A caustic and irritating
material. See also CALCIUM
COMPOUNDS. A common air
contaminant. A powerful caustic to living
tissue. The powdered oxide may react
explosively with water. Mixtures with
ethanol may igmte if heated and thus can
cause an air-vapor explosion. Violent
reaction with (I3203 + CaCl2) interhalogens
(e.g., BF3, CIF3), F2, HF, P2O5 + heat, water.
Incandescent reaction with liquid HF.
Incompatible with phosphoms(V) oxide.
Potential Exposure
Calcium oxide is used as a refractory
material; a binding agent in bricks; plaster, mortar, stucco,
and other building materials. A dehydrating agent, a flux in
steel manufacturing, and a labora
Shipping
UN1910 Calcium oxide, Hazard class: 8; Labels:
8-Corrosive material.
Incompatibilities
The water solution is a medium strong
base. Reacts with water, forming calcium hydroxide and
sufficient heat to ignite nearby combustible materials.
Reacts violently with acids, halogens, metals.
Waste Disposal
Pretreatment involves neutralization with hydrochloric acid to yield calcium chloride.
The calcium chloride formed is treated with soda ash to
yield the insoluble calcium carbonate. The remaining brine
solution may be discharged into sewers and waterways
Check Digit Verification of cas no
The CAS Registry Mumber 1305-78-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,3,0 and 5 respectively; the second part has 2 digits, 7 and 8 respectively.
Calculate Digit Verification of CAS Registry Number 1305-78:
(6*1)+(5*3)+(4*0)+(3*5)+(2*7)+(1*8)=58
58 % 10 = 8
So 1305-78-8 is a valid CAS Registry Number.
InChI:InChI=1/Ca.O/q+2;-2
