ECOLOGICAL CHEMICAL CHARACTERISTICS OF DEICING MATERIALS AND TECHNOLOGY OF THEIR SAFE APPLICATION - Студенческий научный форум

XII Международная студенческая научная конференция Студенческий научный форум - 2020

ECOLOGICAL CHEMICAL CHARACTERISTICS OF DEICING MATERIALS AND TECHNOLOGY OF THEIR SAFE APPLICATION

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In cities where vast heaps of people, industrial enterprises and traffic are concentrated, whole new ecosystem appears. It is characterized with high level of pollution, specific heat regime, vegetation depression, soil pollution. This results in the necessity to carryout high priority measures on preservation of natural amenities. With pollution accumulation the organic matter concentration in open water increases, in its turn it results in complication and cost increase of drinking water purification. Pollutant accumulation process in natural habitat at specific time intervals can result in irreversible changes. It is necessary to develop measures on the mentioned influence, particularly obligatory observation of the requirements of the highways winter cleaning technology, the content and reagents consumption at different temperature ranges, and also exclusion of rotary snow clearance with penetration of pollutants into the green areas.

Industrial city ecology is determined with all region condition. For cities there are definite critical indicators of pollution volumes (so called - ecological capacity), at crossing them the processes of various deformation and instabilities appear. One can speak about critical characteristics for atmosphere, open and underground aquatic medium, soil, green planting, industrial zones, waste dumps, public health.

The necessity to provide the functioning in the atmospheric precipitation conditions at negative temperatures of the environment in winter period appears. It is known that snow cover accumulates the considerable part of atmospheric contaminations; it is an indicator of environmental footprint on the environment. One uses different reagents to struggle with winter snow cover and road slippery surface.

Fresh snow with applied sandy salt mixture is compacted significantly slower and is rolled to vehicles wheels then pure snow. It was proved experimentally that slowing down the process of compacting and rolling of snow is obtained due to the presence of chlorides in sandy salt mixture. Such deicing chemical agents as sodium chlorides, calcium chlorides, magnesium chlorides and potassium chlorides got the widest application. According to their composition they can be homogeneous or mixed in different proportions. These reagents application into snow provides its density increase because at the contact with reagents part of snow changes into solution. This results in snow volume decrease.

Deicing reagents that are used for road processing in winter period are certified and they do not harm populated area ecology.

The list of deicing materials includes - deicing reagents (hard, combined and liquid), and also friction deicing materials, corresponding to the main requirements to the composition and properties. Deicing reagents (DR) are hard (granular), combined (combination of hard chemical and friction components), and also liquid (solutions) chemical artificial means, distributed on the surface of road cover to struggle with winter slipperiness (prevention of its formation and liquidation) by means of interaction with snow-ice depositions. The possibility to support in the admissible state elements Road Facilities Object

Reagents in the process of their exploitation in winter period is provided with ice (snow) melting and formation of water solutions DR (salts), with freezing temperature lower than water freezing temperature .

Friction materials (deicing) - hard, granular, insoluble (slightly soluble) in water materials, distributed along the surface of road covering to liquidate winter slippery formation by means of increase of adhesion coefficient of wheels of vehicles as a result of increase of roughness of snow ice depositions.

Combined materials (combined DR) are hard (granular) means having in their composition chemical deicing reagents (DR), and friction materials.

Liquid reagent is base on calcium chloride and sodium chloride, mass fraction of soluble salts, % (concentration), in the range of 27-29%: calcium chloride - in the range of 22-23%, sodium chloride in the range of 5-6% correspondingly.

Hard DR is hard polycomponent deicing reagent on the base of composition of calcium chloride with other chlorides (sodium and potassium) and sodium formate: mass fraction of calcium chloride is not less than 20%; sodium chloride is not more than 75%; calcium chloride - not more than 20%; sodium formate - not less than 5% by mass correspondingly (MPKtb.).

Hard polycomponent deicing reagent on the base of composition of calcium chloride and sodium chloride: mass fraction of calcium chloride is not less than 20%; mass fraction of sodium chloride - not more than 80% by mass correspondingly (XKHtb.)

Hard polycomponent deicing reagent on the base of composition of calcium chloride with other chlorides (sodium and potassium) and sodium formate: mass fraction of calcium chloride is not less than 15%; sodium chloride - not more than 80%; potassium chloride - not more than 10%; sodium formate - not less than 5% by mass correspondingly (MPtb.).

Friction materials (auxiliary) include: small granite macadam with fraction 2-5 mm, which is considered as nrM for definite weather conditions in the traffic way.

Combined material DR is hard combined deicing reagent on the base of composition of calcium carbonate (crushed marble) and sodium formate (formiate): mass fraction of calcium carbonate is 50-80%; sodium formate - 20-50% by mass correspondingly (KP1tb.)

Hard combined deicing reagent on the base of composition of calcium carbonate (crushed marble), and sodium formate (formiate) and sodium chloride (eadible salt): mass fraction of calcium carbonate is 20-50%; sodium formate - 10-30%; mass fraction of sodium chloride - not more than 60% by mass correspondingly.

Hard combined deicing reagent on the base of composition of calcium carbonate (crushed marble), sodium formate (formiate) and sodium chloride (eadible salt) with addition of chlorides (calcium and potassium): mass fraction of calcium carbonate is 20-50%; sodium formate - 10-30%; mass fraction of sodium chloride - more than 50%; mass fraction of chlorides (calcium and potassium) - not more than 20% by mass correspondingly.

The sphere of control measures includes obligatory constant, systematic estimation of quality of deicing materials (incoming control), their technological and ecologic characteristics, including chemical content, physical and chemical, physical and radio ecologic indicators. Duration of carrying out the incoming control of the set DM must not exceed 5 (five) working days from the moment of sampling. Sampling must be done monthly not later than 3 (three) working days after the supplier finishes the shipment of the month volume DM according to delivery schedule which is the State contract supplement. It is possible to analyze the DM at the expense of the supplier in some other specialized certified in accordance with procedure established by law laboratories. The laboratories where the quality control is carried out must be certified by the dedicated federal agency of control and supervision in the sphere of environment and ecosystem exploitation.

After passing the procedure of the State Environmental Review of the Federal level and the presence of approved in the established procedure of positive opinion the present technology can be applied in the winter management system of RFO. Control over the implementation of the present technology is executed by the designated authority in the sphere of the environmental protection of the federal level.

Technology and treatment procedure of road covering with deicing materials:

- To treat the traffic way of RFO (primary - before snowfall start and basic during carrying out snow clearing activities) one uses hard and liquid DR, which is necessary to distribute observing strictly the set standard of road covering treatment for one technological cycle. The hard deicing reagents are used as the basic deicing reagents.

- Small granite macadam of fraction 2-5 mm is considered as basic or additional deicing material at definite weather conditions on the traffic way. On the pavements, house areas, public transport stops to eliminate the winter slippery only the application of combined DR is permitted.

- The traffic way treatment with liquid DR must be carried out by special machines of type «MKflC-2204» (or similar technique), with automatic control of distribution.

- The traffic way treatment with hard deicing reagents must be done with the machines of type «KyM-5551», equipped with the system of automatic control of distribution.

-The treatment with granite macadam of fraction 2-5 mm and combined DR is done with machines of type «KyM-5551», and machines of type «nP-1».

- The extension of the prior treated zones of slowing down before crossings, above ground pedestrian crossings, traffic control posts is set for roads with maximum legal speed up to 60 km/h - not less than 150 m, for roads with maximum legal speed more than 60 km -not less than 200 m. To do these technological operations is necessary to keep machines-reagent distributors loaded with DR in the amount sufficient for all attached area treatment.

- Deicing reagents DR, distributed on the traffic way surface according to the present technology mixed with snow by the moving transport wheels, during the definite time (up to 3 hours), keep on the road snow pack in loose condition and prevent its rolling to road covering surface.

- At mechanized sweeping the treated with reagents snow layer is easily removed from traffic way by plows and brushes of sweeping machines.

If one gets the forewarning about icy sports genesis danger from meteorological authority full treatment of traffic way must be done before the beginning of ice-forming phenomena. When you get warning about possible transfer of air temperature via 0 °C to the negative meanings and possible formation of icy sports (ice film, glassy ice), particularly at night time, preventive DR treatment must be done. It need not be accompanied with sweeping of the traffic way in case of atmospheric precipitation absence. This technological operation is done by order of the strategic city main office. Consumption rates correspond to minimum values for temperature range from 0 to -2°C. At receiving warning about possible glaze formation in the periods of the most intensive movement of vehicle and atmospheric precipitation presence, as a rule, at the day time the DR preventive treatment must be done before traffic way sweeping. This technological operation is done by order of the strategic city main office. At obtaining the forewarning about snowfall from meteorological authority before precipitation the primary DR treatment of the most dangerous for vehicle movement areas of RFO (steeps and up-hill gradients, bridges, overpasses, tunnels, stop ways, etc.) must be done. At snowfalls up to 3 sm: full DR treatment of traffic way is done before snowfall starts and after every cycle of mechanized sweeping of traffic way. This operation must start from the right-hand lane along which traffic routs of public transport take place. Clustering of salt solutions on the bands of electro transport traffic routs is not permitted.

At heavy and long snowfalls and snow cover depth more than 2 sm only hard DR are applied (including combined DR). In case of special order of the strategic city main office hard DR application is done in combination with liquid DR and / or macadam with fraction 2-5 mm.

The possibility of random treatment of traffic way is foreseen, beginning from the most dangerous for vehicle movement areas - stop ways areas at crossings, square foot allocations at the public transport stops; steeps, up-hill gradients, bridges, overpasses, etc. In the periods of snowfalls at accumulated (or predicted) values of fallen snow more than 3 sm full treatment of the RFO traffic way is dine by hard DR. At application of hard DR in combination with liquid DR distribution density of each type of DR is defined according to order of the strategic city main office (Table 6).

Table 6 - Density of treatment with hard DR regulated by the present technology

Reagent type Units of measurement Reagent consumption at air temperatures, °C

from 0 to -4 from -4 to -8 from -8 to -12 from -12 to -16 from -16 to -20

Hard g/m 2 20-30 30-50 50-60 60-70 70-80

Note: application of hard DR at air temperature from -16 °C to -20 °C is reasonable together with granite macadam with fraction 2-5 mm at special order of the strategic city main office.

At snowfall and air temperature jump (in the range of negative temperatures) the DR consumption rate is determined taking into account air temperature gradient during 6 hours, preceded snowfall by interpolation method (Table 7).

Table 7 - Density of treatment with combined DR regulated by the present technology

Reagent type Units of measurement Reagent consumption at air temperatures, °C

from 0 to -6 below -6

Hard combined DR (at this density of distribution must not exceed 200 g/m 2). 2 E g/ 80-100 100-120

Treatment with granite macadam with fraction 2-5 mm:

At air temperatures below -15 °C one should treat the streets areas especially dangerous for vehicle movement, - stop ways areas at crossings, square foot allocations at the public transport stops; steeps, up-hill gradients, etc.

At air temperatures below -20 °C in the periods of snowfalls full treatment of traffic way of RFO is done. The similar technological operation must be done by the recommendation of the strategic city main office with consumption rate marking.

Density of distribution of granite macadam with fraction 2-5 mm is 100-200 g/m 2, total volume of application on the traffic way is not more than 15000 tons in a season. At the necessity of treatment of the traffic way with granite macadam with fraction 2-5 mm in combination with hard DR the density of distribution is defined according to the order of the strategic city main office.

Liquid and hard DR are delivered by the transport of different types according to the working regulations of shipping goods on the given transport type. Production marking is done according to the current standards and marking regulations of the enterprise-producer of reagents.

Liquid deicing reagents must have guaranteed storage life - not less than 24 months starting from the day of manufacture. Storage is realized according to technical standard documents of manufacturing enterprise, stipulated by current legislation, in tanks with capacity from 6m3 and more. After the expiry of guaranteed storage life the product must be inspected for the purpose of guaranteed storage life extension for one year. Filling up the machines-distributors with reagent is done by natural flow or by special pumps.

Hard and combined deicing reagents are left in the specialized soft containers of type «MCR» with a nett capacity up to 1000 kg, in polypropylene bags with weight from 25 kg and/or other types of consumption package, produced according to standard technical documents, stipulated by current legislation. Hard and combined DR must have guaranteed storage life - not less than 24 months from the day of manufacture. After the expiry of guaranteed storage life the product must be inspected for the purpose of guaranteed storage life extension at the condition of observations of rules and sealing capacity of producer’s package.

Hard and combined deicing reagents are kept in closed dry stores excluding direct sunlight penetration. One should not allow reagents having direct long-term contact with air till their consumption moment. In the open platforms the keeping of hard DR packed into special soft sealed containers (packages) located on trays is allowed. The platform on which packages and soft containers must be cleaned from protruding objects.

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