Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
  • A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
  • A62D3/33—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by chemical fixing the harmful substance, e.g. by chelation or complexation
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
  • C03C1/002—Use of waste materials, e.g. slags
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
  • A62D2101/40—Inorganic substances
  • A62D2101/43—Inorganic substances containing heavy metals, in the bonded or free state

Definitions

• the present invention relates to a method for treating waste containing mercury (Hg) , cadmium (Cd) and lead (Pb).
• the waste kan be discharge lamps, batteries, thermometers, amalgam residues and apparatus.
• the environ ⁇ mentally hazardous heavy metals are trapped in secure che ⁇ mical bonds with elementary selenium (Se) in order to become environmentally neutral.
• Cd + Se * CdSe, cadmium selenide Some of the waste, as for example fluorescent tubes and thermometers, contains resources which contribute with protective gas (argon and krypton) and glass melt. The different metal selenides as well as other metal residues will be encapsulated in the glass melt or vitrified. The latter implies that the glass melt functions as a solvent for the bonds between the atoms and that the metals pass into the glass.
• the toxic substances injurious to the environment - the heavy metals - are then finally taken care of and rendered harmless.
• the glass billet which is the end product, can be deposited on an ordinary dump.
• Mercury (Hg) is a very poisonous heavy metal which can damage the central nervous system. It causes in small amounts headache and nervous problems, in larger amounts convulsions and a coma condition which can end in death.
• the invention refers to a method of eliminating the heavy metals Hg, Cd, and Pb via a chemical bonding with selenium (Se) and glass (Na2C ⁇ 3 + SiC ⁇ 2), so called vitrifi ⁇ cation.
• the device in which the chemical reaction is accom ⁇ plished, is an electrical heat treatment oven with a capa- city to attain over 900 °C, a so called autoclave which is completely closed and preferably at a pressure below that of the atmosphere.
• the hazardous waste to be rendered harm ⁇ less considering the contents of heavy metals is placed in the oven.
• This waste can consist of light sources containing Hg and largely consisting of glass.
• Amalgam residues are com ⁇ posed of 50 % Hg.
• Batteries can contain Hg as well as Cd but have a casing of metal.
• Thermometers contain pure Hg but with a casing of glass.
• Mercury breakers include Hg within a casing of glass.
• Modern types of electrically operated hand tools contain rechargeable batteries with Cd.
• the oven is now provided with selenium (Se) which, if necessary, can be contained in a special ampoule made of glass or aluminium.
• Se selenium
• the molecular weights of Hg, Cd and Se are 200.61, 112.41 and 78.96 kg/kmol, respectively.
• Se selenium
• the vaporizing temperature of Hg is 357 °C and, therefore, the evaporation proceeds quickly.
• Selenium is that element which shall bind the heavy metals in vapour phase at 680 °C, the reaction being a sublimation which proceeds rapidly.
• the mercury in fluo- rescent tubes, thermometers and other glass encasings becomes accessible to the chemical reaction only at the melting point of the glass which is 800-900 °C.
• Prerequisite of the complete binding is a certain surplus of selenium in the oven.
• 10 g Hg at least 3.95 g Se is required.
• the reaction is accelerated by the high temperature and the reaction proceeds substan ⁇ tially to the right according to the following:
• the mercury selenide consists of very dark, small crystals which can be observed in a scanning electron microscope. It can be solubilized only by aqua regia or boiling sulphuric acid. The reaction proceeds best with deficiency of oxygen since oxides then cannot be formed.
• the argon or krypton gas included in the fluorescent tubes serves as a protective gas and facilitates the forma ⁇ tion of HgSe.
• the glass included in the waste material can be supplemented with separately supplied scrap-glass, prefera ⁇ bly coloured glass.

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Business, Economics & Management (AREA)
• Toxicology (AREA)
• General Health & Medical Sciences (AREA)
• Health & Medical Sciences (AREA)
• Emergency Management (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Processing Of Solid Wastes (AREA)
• Manufacture And Refinement Of Metals (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20381192

Family Applications (1)

Country Status (3)

Cited By (3)

Citations (3)

• 1990
  • 1990-12-14 SE SE9003990A patent/SE501043C2/sv not_active IP Right Cessation
• 1991
  • 1991-12-16 AU AU91107/91A patent/AU9110791A/en not_active Abandoned
  • 1991-12-16 WO PCT/SE1991/000873 patent/WO1992010240A1/en active Application Filing

Patent Citations (3)

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