Экологические и
метеорологические проблемы больших
городов и промышленных зон
Turgumbayeva R.H.
The
Kazakh National Pedagogical University named after Abai, The Republic of
Kazakhstan
Evaluation the
pollution of environment by inorganic dust during the
thermal preparation and agglomeration of phosphoritic raw material
The phosphorus’ factories in Republic Kazakhstan are working on the
phosphoritic rawes that contain not more phosphoric oxide (about 20% Р2 О5)
and another components. The technological process production of yellow
phosphorus is foresee preliminary preparation of raw: breaking up,
classification, drying, the thermal’s preparation of phosphorus, agglomeration.
During the transportation and therma’s
destroying of phosphorite at the some time with gas components forms
considerable quantity of dust. This dust have mechanical’s origin and have a
great size of part.
It is important that independently of method of chemical preparing
phosphorus of raw materials take place the same processes –destroying of
carbonates, hydrocarbonates, phase transformations.
The furnace gases at exit from the furnace content from 5 to 120 g/nm3
of polydisperse dust. The dust is connected [1, 2] with three bases processes
are occuring in phosphorus furnace: the interaction at high temperatures of raw
materials between itself and with
reducing agent, evaporation of oxides and sublimation of fusible components, a
mechanical breaking of mix material during their transportation in batchers.
On phosphorus enterprise of Kazakhstan
formation of dust is the result of the processes –crushing, the sorting, the
thermopreparation, the transportation batch materials (phosphorite, agglomerate, quartzite,
coke) for the electrotermical treatment to the yellow phosphorus. This dusts are not
need in blending and a simple make up the deficit fraction 0,5 – 0 mm in
agglomix. Besides that they have in their structure P2O5 and a combustible carbon. Therefore it dusts
can be used as add that harden agglomerate. Basic harmful
emissions are dust of phosphorite, quartzite, coke. agglomerate,
compounds of phosphorite and fluorine. Dusts of phosphorite,
quartzite and coke thrown out to atmosphere together
with dust of mix material, including dioxide of silicium under 20%,
identify as inorganic dust including SiO2 .
The
studies of real ecological situations on the basis of the data of control of
the man-induced changes of the environment present one of the main tasks of
engineering-ecological analysis of natural – technical geo-system.
At present there is no generally accepted method of evaluation of impact
on the environment which allows characterization of an enterprise construction
project as well as an enterprise activity in the period of operation. An
unbiased evaluation of the system state rests on the group of indices, having a
different physical nature and basing on different methods of measurements and
control.
With the aim of quantitative evaluation of atmosphere pollution by
phosphorus oxide we have used Pasquille-Gifford empiric model based on the
assumption of constant interference-free point source of a definite capacity
having homogenous characteristics of atmospheric dispersion. This model is
based upon the conception of concentration of admixture emitted by a constant
point source into atmosphere as of a stream with vertical Gaussian
distributions and transverse to wind:
where
q – admixture concentration in the given point of space; x,v,z – Cartesian coordinates, axis z – up -, axis x – downwind;
- source of emission capacity 
- vertical and transverse dispersions of
admixture cloud; u – wind velocity
averaged for the layer of mixing; ƒf and ƒw –
deduction for cloud depletion at the expense of dry deposition of admixture and
its scavenging (текст не читается) effective altitude of the
source (i.e. altitude with consideration
of the original rise of the overheated stream). Exponents sum in this formula
corresponds to the ground surface not absorbing the admixture, in case of
absolute absorption exponents the difference is observed. The main content of
the model is presented by numerous summarizing experimental data, specific
functions 
and 
and
expressions for h, ƒf and ƒw.
Actually sources of emission are not exactly point sources, but for the
purposes of simplification of mathematical description it is possible to assume
they are. The nature of specification of the chosen model allows taking into
consideration the peculiarities of local meteorological conditions and
calculate the distribution of the pollutants concentration in current
meteorological conditions at various values of emission capacity [3, 4]. In
this work we have used the data on technical characteristics of the emission
sources and averaged value of polluting substances emissions capacity of the
enterprise in the conditions of its actual operation. Calculations were made by
means of universal integrated suite MATLAB [5].
Figuгes
1 and 2 demonstrates two- and three-dimensional spatial dispersion of inorganic
dust in the atmosphere. Emission source point corresponds to the coordinates x = 0, y = 0. It is shown that the inorganic dust spray is distributed
over the whole territory adjacent to the plant gradually decreasing with the
distance from the source of emission down to 0,35 fractions of maximum
permissible discharge (MPD) at the range of 20 km.
Figuгe 1 -
Two-dimensional dispersion of inorganic dust from department of thermal
preparation and agglomeration of phosphorites in the atmosphere.
Figuгe 2 –
Three-dimensionall emission of the inorganic dust from department of thermal
preparation of phosphorites in the atmosphere. Axes x and y - distances, kms;
axis z – concentration, fractions of
MPD. Conventional point source of emission corresponds to coordinates x =0, y
=0.
The model allows prediction of the degree of atmospheric air pollution
at different emission capacities and to obtain the data on the distribution of
polluting spray and determine the zones of danger for human beings.
Calculations for the emission capacity in the outlet of the conventional source
equaling to 37,8 fractions of MPD demonstrated, that in the situation, close to
calm at the distance up to 13 km the spray concentration exceeds MPD and in the
residential area makes 0,75 fractions of MPD (figure 3).
The department of agglomeration of phosphorites is throwing up in
atmosphere smaller amount of inorganic
dust by comparing with department of thermal’s of raw materials. Figures 3 and
4 show that emission of the inorganic
dust from agglomeration’s department in the atmosphere in circumstance be
throwing up 7,0 MPD is decrease from 0,14 to 0,11 MPD at the distance 20 km.
Figuгe 3 –
Three-dimensionall emission of the inorganic dust from agglomeration’s
department in the atmosphere. Axes x
and y - distances, kms; axis z – concentration, fractions of MPD.
Conventional point source of emission corresponds to coordinates x =25, y =25.
Figuгe 4 –
Two-dimensional emission of the inorganic dust from agglomeration’s department
in the atmosphere with the indication of areas of danger. On the curves the
values of dimensionless total concentration of dust in the fractions of MPD are
shown.
Thus, the presented results of the calculation of the inorganic dust in
the atmosphere using the empiric model of Pasquille- Gifford allows prediction
the distribution of inorganic dust concentration within the area, i.e. allows
to single out the sites of the contaminated area.
The analysis of the obtained data allows evaluation of the degree of the
atmospheric pollution by emissions of the industrial phosphorite processing
enterprise and gives the opportunity to predict the pollution of surface air at
various degrees of intensity of the inorganic dust and other polluting agents
emissions.
Literature
- Юнусов У.И., Карпенко В. А., Шауберг Г,Г, и др.
Отраслевая методика определения
удельных выбросов вредных веществ в атмосферу на единицу продукции в производстве жёлтого фосфора и термической фосфорной
кислоты. М.: химия. 1984. 94с.
- Юнусов У.И., Карпенко В.А., Сулейменова С. Ж. « Охрана
воздушного бассейна от вредных выбросов фосфорных производств. Учебное пособие. М.: Химия.1985.45
с.
- Методика
прогнозирования масштабов заражения сильнодействующими ядовитыми
веществами при авариях
(разрушениях) на химически опасных объектах и транспорте. РД 52.04.253-90.
Л.: Гидрометеоиздат, 1991, 23с.
- Руководство
по контролю загрязнения атмосферы. / Под ред М.Е. Берлянда, Г.И.
Сидоренко. – Л.: Гидрометеоиздат, 1979. - 448с.
- В.П. Дьяконов. МАТЛАБ 6: учебный курс. СПб: Изд. Питер, 2001.- 592с.