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INVENTION
Russian Federation Patent RU2228227
METHOD removal of mercury waste
Name of the inventor: Borbat VF .; Mukhin VA .; IF Kanushin
The name of the patentee: Omsk State University
Address for correspondence: 644077, Omsk-77, Mira, 55A, Omsk State University, patent office
Starting date of the patent: 2002.10.07
The invention relates to environmental technologies and can be used for recycling of mercury-containing waste, such as waste fluorescent tubes, mercury thermometers, barometers, vacuum gauges and other devices containing mercury in glass envelopes. Method of removal of mercury waste provides for their co-milling in admixture with a grinding medium and the use of sulfur to bind metallic mercury, the method is further used aqueous solutions of ferric chloride (3) podmylnogo hydroxide and sodium hydroxide, and the components are introduced in the following order: a mixture solution ferric chloride (3) from the grinding media in the form of crushed rock portions mercury waste is introduced, they are crushed and milled, and then was added a prepared mixture of elemental sulfur and lye podmylnym sodium hydroxide solution in the following ratio of chemical reactant (based on the 0.1 wt.% . of mercury in the waste), wt%: 10% ferric chloride solution (3) 2.0-3.0; elemental sulfur 0.4-0.6; podmylny liquor 0.1-0.2; 10% Sodium hydroxide 1.5-2.5, it is possible to improve process efficiency by pre-training to reduce its mercury and sulfur mobility to improve its wettability.
DESCRIPTION OF THE INVENTION
The invention relates to environmental technologies and can be used for the disposal of various waste, having in its composition of metallic mercury, in particular, waste fluorescent tubes, mercury thermometers, pressure gauges, vacuum gauges of various types, etc. This kind of waste belonging to 1 class of hazard (Mercury and its compounds Series "reviews the scientific literature on toxicity and hazards of chemicals", Moscow, 1998, -. S.1-92).
The number of worn-out fluorescent lamps in the millions and growing every year. Each lamp can contain up to 0.6 grams of mercury. During storage of spent lamps and other devices, or export them to a landfill there is a risk of depressurization glass shells and getting toxic mercury and mercury vapors into the environment. Consequently, reliable demercurization mercury waste is essential.
Most often, recycling wastes and mercury demercurization effected by heat treatment and crushing them with subsequent condensation of mercury vapor and metal yield again (secondary) of mercury or chemical treatment of metallic mercury with transfer poorly soluble in non-toxic chemical compound.
Published and applied method demercurisation fluorescent lamps, which after crushing lamps mercury sublimated, followed by condensation and obtaining secondary mercury (RF Patent 2087572, cl. C 22 B 43/00 publ. 1997.08.20). The danger of leakage of hot mercury vapor during depressurization equipment and high energy intensity is not always possible to use this method. In addition, untreated secondary mercury is difficult to sell.
Known method and the removal of mercury waste expect their co-milling in admixture with the sulfur to a particle size of 5 mm, and the sulfur flow rate is from 0.1 to 5% by weight of the waste (Japanese Application №3-5236, cl. B 09 B 3 / 00, 1991). After adding water, the mixture of cement and cured. Because metallic mercury mobility and inertia takes a long dry sulfur agitation to go all the mercury in its sulfide, a partial transfer of mercury.
The closest to the claimed method is the removal of mercury lamps, comprising co-milling them with gray, grinding media, water and non-toxic particulate catalyst to increase the contact surface of the mercury and sulfur (RF patent №2156172, Cl. B 09 B 3/00 from 22 in 43/00, 2000.09.20). However, this method is not sufficiently effective, because water used for wetting the mercury does not preclude its mobility, resulting in a reaction with sulfur in the presence of mercury proposed even a catalyst may proceed long enough and incompletely.
The present invention is the ability to increase process efficiency by pre-training to reduce its mercury and sulfur mobility to improve its wettability.
This technical result is obtained due to the fact that in the process of removal of mercury waste, based on their joint milling with grinding media and the use of elemental sulfur to bind metallic mercury primarily provide reduction of mercury mobility through joint grinding of waste lamps and other mercury-containing waste from 10-20 % aqueous solution of ferric chloride (3) and the gravel fraction 100-150 mm.
Within 15-30 minutes after the last portion of the waste and the intensive grinding in a sealed horizontal rotary drum inside introduced pre-prepared mixture of elemental sulfur with podmylnym liquor - waste product of soap and sodium hydroxide solution. The ratio of input chemicals include - per 0.1 wt% of the mercury in the waste mass.%:.
10-20% aqueous solution of ferric chloride (3) 2.0-3.0; 0.4-0.6 elemental sulfur; podmylnogo liquor 0.1-0.2; 1.5-2.5 with 10% sodium hydroxide solution. The process of neutralization is advantageously carried out at ambient 0-18ºS air to prevent the evaporation of metallic mercury.
Using a 10-20% aqueous solution of ferric chloride (3) mercury robs its inherent mobility and provides improved contact with the reagents and the grinding media. Upon contact of mercury with ferric chloride solution (3), the following reaction takes place:
The pH of the system after the completion of the reaction (1) is in the range 0.9-1.2.
Of all of the reaction products mercury only soluble mercuric chloride HgCl 2, the presence of which it is possible in small amounts, the solubility of the remaining is very small, ranging from 10 -3 to 10 -4 g / l of Hg 2 Cl 2 to 10 -6 -10 -7 g / l for Hg 2 O and HgO (Yu.Yu.Lure, Handbook of analytical chemistry, chemistry, 1979 s.92-101).
After milling is complete, lasting for at least 15-30 minutes, is introduced into the rotary drum premix elemental sulfur podmylnogo liquor and 10% sodium hydroxide solution. To prepare the mixture is stirred calculated the amount of sulfur in podmylnom liquor, thus eliminating sulfur hydrophobicity and provides good wetting her, facilitates the flow of fullness subsequent reactions. Addition of 10% sodium hydroxide solution gives rise to a mixture of several products, including sodium sulfide and polysulfide required to transfer the reaction products (1) insoluble, non-toxic mercury and iron sulphides.
(Nekrasov BV Fundamentals of General Chemistry T.1 M .: Chemistry, 1965, p.331..;
Ugai JA Inorganic chemistry. -. M .: Higher School, 1989, s.317) The pH of the resulting system is 11,5-12,0.
When mixing system (1) with the mixture (2) goes into iron hydroxide precipitate Fe (OH) 2 and Fe (OH) 3 (solubility of 10 -4 to 10 -8 g / l) and insoluble precipitates FeS and Fe 2 S 3 (solubility 10 -8 and 10 -6 g / l, respectively). In the first previously formed precipitates mercury Hg 2 Cl 2, Hg 2 O and transferred to HgO practically insoluble sulfides of mercury Hg and 2 S HgS (solubility 10 -21 and 10 -24 g / l, respectively). These sulfides are some of the mercury compounds poorly soluble and therefore non-toxic.
After mixing and grinding systems (1) and (2) the resulting product is pH 6-8, and because the smallest HgS has a solubility of all known sulphides, all other sulfides and pass it does not remain unbound ions Hg 2+ potential values and the pH of the resulting product are diagrams in 
-pH corresponding to the existence of mercury sulphide HgS (Geological Survey Professional Paper 713. Mercury in the Environment, United States Department of Interior, Washington DC, 1970, p.20; Tinsley IV Behavior of chemical pollutants in the environment M .: World. 1982, p.112.).
The process is as follows.
The apparatus for the removal of mercury waste, as is preferable to use a horizontal rotating drum, allowing for seal - perhaps fixed or mobile concrete mixer, pre-loaded some for up to a predetermined amount of mercury in the waste volume of 10-20% (3) of a solution of ferric chloride and gravel fractions 100 -150 mm. The number of revolutions of the drum may vary depending on the nature neutralizes mercury-containing waste. During the processing of repeatedly changing the direction of rotation of the drum to improve the completeness of the reactions.
Next, the rotating drum is gradually charged with the calculated amount of mercury-containing waste to at least download and destruction of lamps and other waste all mercury had time to slip into the ferric chloride solution. After 15-30 minutes after the last open lamp load during rotation of the drum and added to the prepared mixture of elemental sulfur and lye podmylnym sodium hydroxide and stirring was continued for an additional 30-60 minutes. Thereafter, the resulting mixture is loaded into a vehicle and transported to the test site map IV hazard class.
Adopted boot sequence components eliminates the ingress of mercury vapor in the atmosphere
print version
Publication date 19.02.2007gg
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