First, emergency response to leakage

Quickly evacuate personnel from the leaked contaminated area to a safe area and isolate them to strictly restrict access. Cut off the fire. It is recommended that emergency handlers wear self-contained positive-pressure air respirators. And use restricted spaces such as sewers, flood drains.

Small leak

Adsorb or absorb with sand or other non-combustible materials. Large spills: build dikes or containment pits.

Waste disposal methods

It is recommended to dispose by incineration. The waste is incinerated after being mixed with other fuels. The combustion should be sufficient to prevent the generation of phosgene. The nitrogen oxides in the incinerator exhaust are removed by an acid scrubber.

Second, protective measures

Respiratory protection

When the concentration in the air exceeds the standard, a direct gas mask (half-mask) should be worn. Wear an air respirator for emergencies or evacuation.

Eye protection

If necessary, wear chemical safety glasses.

Body protection

Wear anti-poison overalls.

Hand protection

Wear chemical resistant gloves.

other

Smoking, eating and drinking are prohibited at the work site. After work, bathe and change clothes. Store contaminated clothes separately and wash them for later use. Pay attention to personal hygiene.

Third, first aid measures

skin contact

Remove contaminated clothing and rinse skin thoroughly with soap and water.

eye contact

Lift your eyelids and rinse with running water or saline. Seek medical attention.

Inhale

Quickly leave the scene to fresh air. Keep your airways open. If breathing is difficult, give oxygen. If not breathing, give artificial respiration immediately. Seek medical attention.

Ingestion

1. If the patient is about to lose consciousness, has lost consciousness or is convulsed, do not feed anything by mouth.

2. Do not induce vomiting.

3． Drink 250 ml of water to dilute the stomach.

4． If the patient spontaneously vomits, tilt his body forward to reduce the risk of aspiration and give him water repeatedly.

5． If breathing stops, immediately give artificial respiration by the trained person, and stop CPR with heartbeat.

6. Quickly send the patient to an emergency medical unit. Drink plenty of warm water, induce vomiting, and consult a doctor.

The most important symptoms and harmful effects:

Very high concentrations of exposure may cause loss of consciousness and death.

Protection of emergency personnel:

When the patient inhales and swallows toxic substances, do not use mouth-to-mouth artificial respiration directly. Use a unidirectional air-supply pocket mask and other medical equipment to perform artificial respiration. First-aid should be worn in safe areas while wearing Class C protective equipment.

Fire fighting methods:

Mist water, sand, foam, carbon dioxide. Fire fighting measures Suitable fire extinguishing agents: chemical dry powder, foam, carbon dioxide, water mist

Special hazards you may encounter during fire fighting:

1. Above 120 degrees, its vapor is flammable.

2. Toxic gas will be decomposed during fire, which is dangerous.

Special fire fighting procedures:

1. Sprinkle water to cool the container exposed to the fire, and spray water to flush the leakage from the exposed area.

2. When such a substance catches fire or is caught in a fire: Do not extinguish the fire unless it can stop its spread. If the fire is out of control or the container is exposed to the fire, the area within 2500 feet must be evacuated.

冷却 Cool the container with plenty of water until the fire is extinguished. (Erg2002)

4． Do not flush the spilled material directly, as splashing may occur (erg2002)

Special protective equipment for firefighters:

1. Post-combustion toxic products: Post-combustion products include toxic gases and vapors (such as hydrogen chloride, phosgene and carbon monoxide).

The vapor of methylene chloride is heavier than air, and it can float a considerable distance to the ignition source and burn it back.

Dichloromethane has the advantages of strong solubility and low toxicity. It is widely used in the production of safety film, polycarbonate, and the rest is used as a coating solvent, metal degreasing agent, aerosol spraying agent, polyurethane foaming agent, release agent, and release agent. Paint.

Dichloromethane is a colorless liquid. It is used as a reaction medium in the pharmaceutical industry for the preparation of ampicillin, oxy benzyl penicillin, and vanguardmycin. It is also used as a solvent in film production, a petroleum dewaxing solvent, an aerosol propellant, Organic synthetic extraction agent, foaming agent for foam production such as polyurethane, and metal cleaning agent.

Dichloromethane is mainly used in film production and medicine in China. Among them, the consumption for film production accounts for 50% of the total consumption, the pharmaceutical sector accounts for 20% of the total consumption, the cleaning agent and chemical industry consumption accounts for 20% of the total consumption, and the other aspects account for 10%. Dichloromethane is also used as a refrigerant in industrial refrigeration systems, but it is very harmful. It can produce highly toxic phosgene when it comes in contact with open flames or hot objects. In the case of humid air, it can hydrolyze to form a trace of hydrogen chloride, and light can also promote hydrolysis and enhance the corrosion of metals.

For grain fumigation and refrigeration of low-pressure refrigerators and air-conditioning units. It is used as auxiliary foaming agent in the production of polyether urethane foam and as a foaming agent for extruded polysulfone foam.

Dichloromethane is also used to make decaffeinated coffee. Coffee is first steamed to dissolve the caffeine and float on the surface. Then use methylene chloride to remove the caffeine.

preparation

Natural gas chlorination method Natural gas reacts with chlorine gas. After absorbing hydrogen chloride as by-product hydrochloric acid after water absorption, residual traces of hydrogen chloride are removed with lye, and then dried, compressed, condensed, and distilled to obtain a finished product, in which chlorine gas is 100% 4000, natural gas (standard condition Bottom), methane content 97% 1000m3 / t, liquid alkali 100% 274.

Chloromethane chlorination method Chloromethane reacts with chlorine gas under 4000 kW light to form dichloromethane, which is washed with alkali, curled, condensed, dried and rectified to obtain the finished product. The main by-product is chloroform. Chloromethane ≥98% 746, liquid chlorine ≥99.5% 854, caustic soda 30% 221.

Industry generally synthesizes by chlorination of methane. Methane is chlorinated to obtain a bunch of mixtures including four kinds of methyl chloride. However, since the distances of their respective boiling points are relatively large, they can be conveniently separated and purified by ordinary fractionation techniques.