CS219734B1 - Method of limitation of the hydrogen sulphide exhalations by preparation and treatment of the bitumen and sulphur mixture - Google Patents

Description

Method for reducing hydrogen sulfide exhalation from bitumen and sulfur mixtures resulting from the preparation and processing of these mixtures. The purpose of the invention is to suppress the formation of hydrogen sulphide exhalation during the heat treatment of these mixtures at temperatures of 115 to 175 ° C. This is achieved by the following additives, which are added to the mixture at the latest with the addition of sulfur:

1. Oxide and / or monovalent metal salt and ammonium chloride;

2. an oxide and / or trivalent metal salt, ammonium chloride and a water-soluble organic base to a solution with a pH of more than 8.

BACKGROUND OF THE INVENTION The present invention relates to a process for reducing hydrogen sulfide emissions in the preparation and processing of bitumen / sulfur mixtures or bitumen / sulfur mixtures with mineral fillers in a pasty or liquid state at temperatures of 115 to 175 ° C.

By adding sulfur to the mixtures of bitumen and minerals used in the construction industry in road construction or in the production of insulating and building materials, a significant improvement in the quality of these mixtures can be achieved. A negative side effect of this technology is the reaction of sulfur and bitumen to form hydrogen sulfide, which worsens the working environment. The higher the temperatures used in the preparation or treatment of the mixtures, the more intensely the hydrogen sulfide is produced. In practice, temperatures of 125 to 150 ° C are used, but local overheating up to 180 ° C cannot be excluded.

Numerous methods have been proposed to suppress hydrogen sulphide such as the addition of activated carbon, copper oxides, cobalt, calcium, zinc, sodium, calcium, copper, cobalt, hydrated forms of iron chloride, organic amines, iodine with ethylene glycol, a combination of organic amines and copper carbonate or zinc oxide, zinc organometallic compounds forming free radicals and quinoid type substances such as hydroquinone. Disadvantages of the known methods of suppressing the development of hydrogen sulfide in the preparation and processing of mixtures of bitumen with sulfur are low efficiency in the use of activated carbon or salts, metal oxides and quinoid type substances, the widespread use of organometallic compounds and organic amines. . The use of more hydrated forms of iron chloride results in the foaming of bitumen due to the distillation of the crystal-bound water, although the suppression of the development of hydrogen sulfide is quite effective in these cases.

The above-mentioned disadvantages are eliminated by the process according to the invention, characterized in that, in the preparation of the mixture, at least 0.001 to 10.3% by weight of the oxide and / or the salt of the trivalent metal are added to the mixture. and ammonium chloride in an amount of 0.02 to 8.6 wt.

In addition to these additives, an organic base may also be added in an amount of 0.02 to 3.7% by weight. soluble in water to a solution with a pH greater than 8.

The presence of ammonium chloride in these mixtures positively affects not only the amount of hydrogen sulphide to be exhaled, but also its rate of formation, which is practically constant throughout the heating of the bitumen / sulfur mixture. When using ammonium chloride, the amount of added organic amines or oxides or salts of monovalent metals can be substantially reduced.

Examples:

To 120 g of a mixture of asphalt A-80 and elemental sulfur in a 4: 1 weight ratio was added 0.4 g of FeaO3, 0.15 g of NH4Cl and 0.012 g of triethanolamine. The mixture was heated at 142 ° C for 2.5 hours. 3.2 g of hydrogen sulfide were released as the mixture was heated. Without the addition of the above chemicals, 48.6 mg of hydrogen sulfide was released under the same conditions, and 15.9 mg of hydrogen sulfide for only iron oxide and triethanolamine.

To another mixture of asphalt A-80 and 155 g elemental sulfur containing 24.8% sulfur was added 0.3 g ZnO and 0.2 g NH 4 Cl under the same conditions as in the previous case. The development of hydrogen sulfide was suppressed from the original 68.9 mg to 7.6 mg, without the addition of ammonium chloride to only 38.6 mg.

To a mixture of 138 g of asphalt B-80 and 47 g of elemental sulfur at 135 ° C was added 0.3 g of FeSCU.7HaO and 0.1 g of NH 4 Cl, and the mixture was maintained under stirring at 130 to 140 ° C. At that time, 4.8 mg of hydrogen sulfide was exhaled versus 86.4 mg without the addition of chemicals and 29.8 mg if ferrous sulfate was added.

The invention can be used in the construction industry for the preparation of bituminous coatings of roadways, insulating and building materials.

Claims (2)

Method for reducing hydrogen sulphide exhalation in the preparation and treatment of mixtures of bitumen with sulfur or of mixtures of bitumen with sulfur and mineral fillers in a pasty or liquid state at temperatures of 115 to 175 ° C, characterized in that in the preparation of the mixture % oxide and / or salt of mono- to trivalent metal in an amount of from 0.001 to 10.3 wt. and ammonium chloride in an amount of from 0.02 to 8.6 wt. 2. Process according to claim 1, characterized in that, in addition to the addition of sulfur, at least 0.02 to 3.7% by weight of organic base is added to the mixture. soluble in water to a solution with a pH greater than 8.