Reduction Of Dust Emissions Research Articles

Comparative analysis of methods to minimize dust from granite mine dumps

The measures to reduce the concentration of dust from the mine dump are selected. The criteria for their evaluation and factors of significance are identified to compare them and determine the method that will allow gaining the most ecological and economic effect of its implementation. The solution to this problem is possible using the method of the best alternative in multicriteria problems. The advantage of this method is accounting of assessment criteria of dust reduction methods and their factors of significance. The research allows determining the most appropriate method to minimize dust from the mine dumps by the main criteria: economic costs, the specific consumption of the substance used, the possibility of dust collection in the air, dust emission reduction level, the maximum distance from the dump, the emergence of new harmful compounds, the possibility of use in different seasons. It is proved that the dust reduction method, which corresponds to the application of the polymer solution, and is 0.95 has the highest rate of the membership function among others.

Evaluation of the Degree of the Leak-Through of Fine Dust in a Wet Cleaning Abatement Decreasing Dust Systems of Aspiration Schemes in the Building Construction Industry

The article is devoted to the improvement of environmental safety while reducing emissions of dust exhausting by decreasing dusting schemes of aspiration into atmosphere within the construction industry. The use of high- effective dust capturing devices, reducing leakage degree of dust particles thrown out from aspiration cutting dust schemes is one of the most promising and effective ways to decrease dust emissions at the cement producing enterprises. The article shows some summary results of the field power determination for dust emission, dust of sand and expanded clay, leak out of equipment, workplaces and aspiration schemes of expanded clay and cement manufacturing enterprises. The results of the analysis of dust particles with various dimensions and the experimental determination of the degree of dust separating apparatuses’ leaking out was used for design and development of the new wet dust cleaner -separator. The experiments were carried out to get the leakage's degree of dust particles thrown out from this new wet cleaner’ modification at the industrial plants. The statistical treatment of the experimental results allowed us to get dependence of the leakage of dust's particles in these wet dust cleaners - separators within the studied aerodynamic range of work regime. The results showed that the proposed wet scrubbing dust cleaners provide a significant reduction of dust emissions (expanded clay and sand) into the atmosphere from expanded clay and cement manufacturing enterprises. It is recommended to use the results of the development of dust wet cleaning devices in decreasing of dust aspiration schemes in the building construction industry.

Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period

The West African Monsoon (WAM) is crucial for the socio-economic stability of millions of people living in the Sahel. Severe droughts have ravaged the region in the last three decades of the 20th century, highlighting the need for a better understanding of the WAM dynamics. One of the most dramatic changes in the West African Monsoon (WAM) occurred between 15000–5000 yr BP, when increased summer rainfall led to the so-called “Green Sahara” and to a reduction in dust emissions from the region. However, model experiments are unable to fully reproduce the intensification and geographical expansion of the WAM during this period, even when vegetation over the Sahara is considered. Here, we use a fully coupled simulation for 6000 yr BP (Mid-Holocene) in which prescribed Saharan vegetation and dust concentrations are changed in turn. A closer agreement with proxy records is obtained only when both the Saharan vegetation changes and dust decrease are taken into account. The dust reduction strengthens the vegetation–albedo feedback, extending the monsoon's northern limit approximately 500 km further than the vegetation-change case only. We therefore conclude that accounting for changes in Saharan dust loadings is essential for improving model simulations of the WAM during the Mid-Holocene.

Overcoming environmental challenges in the cement manufacturing sector throughcleaner production. A case of Sino Company, Zimbabwe

The paper investigated the extent to which Sino Zimbabwe Cement Company (SZCC) implemented Cleaner Production (CP) options to deal with high emissions and waste emanating from its operations. Research data was collected through questionnaires, interviews, direct observations and document analysis. Two sets of questionnaires were prepared targeting workers and the local community who were direct recipients of pollutants. Semi-structured interviews were conducted with key informants such as the Production Manager, the Human Resource Manager, the Finance Manager, Engineering Manager, the Health and Safety Officer and the District Environmental Management Agency Officer. Research findings revealed a reduction in dust emissions, volume of discharged effluent, residuals of oil contaminants and energy consumption. However, solid waste generation and its subsequent disposal remains a problem. Whilst adoption of CP can be viewed as a panacea to most environmental challenges faced by the organization, more investment is required towards elimination of some sources and cause of waste and emissions generation. Key Words: Waste, Emissions, Cleaner production, Cement production, Legislation

Designs of Corona Electrodes and Methods for Reduction of Dust Emissions from Electrostatic Precipitators

Existing designs of corona elements used in the corona electrodes of electrostatic precipitators are briefly reviewed. Requirements are set forth for corona electrodes, and corona elements are examined. A formula is proposed for evaluation of the influence exerted by the ignition voltage of the corona discharge on variation in degree of cleaning of gases when obsolete corona electrodes are replaced by corona electrodes with type SF-1 elements.

Study of experimental-industrial design of rotary vortex machine

Comparative assessment of machines by the amount of energy consumed is presented in the paper. For comparison, machines for air purification from dust with the particle size of ~ 3-5 microns were selected. All considered scrubbing machines achieve maximum purification efficiency, but with a different amount of energy spent. A machine with guiding elements reaches maximum purification efficiency with energy consumption by 40% less than a machine with a smooth setting. Testing of industrial design was carried out during purification of gas emissions from cement production ingredients, and purification of flue gases of boiler houses. In both cases using machines not only provided a reduction in dust emissions, but also harmful gas impurities. Dust-gas-air mixture, which has been purified in the rotary vortex machine meets the requirements of state sanitary rules and norms, and may be released into the atmosphere. Testing of the machine has shown that rotary vortex machine with guiding elements, installed on the torus surface provides the purification efficiency of up to 98%, which indicates the usefulness of guiding elements in the rotary vortex machine design. Experiments have shown the appropriateness of using the machine in the technological scheme of gas purification since it provides an effective capture of fine particles.

Smart Home Precipitator for Biomass Furnaces: Design Considerations on a Small-Scale Electrostatic Precipitator

With the use of wood pellets becoming more popular for heating in private households, an increase in particulate matter problems across urban areas has been detected. As this contributes to significant health risks, effective reduction of dust emissions will become mandatory even for comparably small heating systems. The smart home precipitator was designed for this scope of application. This paper demonstrates the development steps aiming at a cost-effective precipitator that can be used for central heating processes up to 30 kW. It starts with research on the mechanical design and on the collection efficiency for the development of a space-saving structure with comparable large collection area. In a next step, two different circuit topologies for the high-voltage power supply have been analyzed. The latest and final work step in the design phase was the development of a smart and efficient control algorithm using fuzzy logic for dynamic optimization.

Frequency of Mine Dust Episodes and the Influence of Meteorological Parameters on the Witwatersrand Area, South Africa

Aeolian dispersal of dust from gold mine tailing storage facilities impacts negatively on amenities, human health, and the environment of the Witwatersrand region, South Africa. The present study adopted a multivariate analytical method to quantify the effect of specific meteorological parameters on dust fall emissions, monitored at 22 sites in the central Witwatersrand area. Using meteorological and dust fall data from 2001 to 2010, the relationships between weather and dust fallout deposition rates were explored across the sites at different seasons. Dust deposition rate varied among seasons, with spring months showing the highest levels and frequency. Atmospheric humidity had negative correlations () with dust fall while wind speed showed positive correlations () at the selected sites (). Sites with low influence of relative humidity had higher impact on wind speed. Mean relative humidity below 50% and mean wind speed above 4 m/s were predicted as critical levels for dust episodes incidence at sites that recorded “heavy” and “very heavy” dust fall. For environmental planning purposes, current mitigation measures should be manipulated in relation to levels of air humidity and wind speed for dust emission reduction, especially during spring.

Long-term monitoring of environmental change in German towns through the use of lichens as biological indicators: comparison between the surveys of 1970, 1980, 1985, 1995, 2005 and 2010 in Wetzlar and Giessen

In the years 1970, 1980, 1985, 1995, 2005 and 2010, lichen mapping in the towns of Wetzlar and Giessen in Hesse was performed. The aim was to show the effects of immission load. Despite the application of modified test methods during the study period, the results can still be compared directly because they could be adapted to the requirements of the guidelines of the Association of German Engineers. Even the earlier study results could be interpreted partly within the scope of the guidelines. Parallel to the lichen mapping, comparative examinations of pH on tree bark were carried out. In both towns, the pH of the tree bark has been increasing continuously, presently almost reaching pre-industrial values. The increase was stronger in Wetzlar than in Giessen. In 1970, the lichen vegetation showed a complete depletion. Since then the number of species has risen significantly. This development happened faster and more intensely in Wetzlar. The comparison of the lichen vegetation between 1970 and 2010 also shows an increased existence of species that are favored by hypertrophic air contaminants. In the 2010 survey, some species considered as being promoted by global warming were found for the first time. The increase of the bark pH can be explained by the decreasing acid pollution, primarily SO2. This is also assumed to be the main cause for the increasing number of lichen species. An explanation for Wetzlar's advantage is that the acid pollutants had been neutralized by a local industrial emittent of lime dust. With the reduction of dust emissions in Wetzlar due to the installation of filters, the bark pH in both towns steadily converged in the reference period. An examination of pre-industrial lichen studies shows that in both towns the original state of lichen vegetation has not been restored yet.

The Asian Dust Aerosol Model 2 (ADAM2) with the use of Normalized Difference Vegetation Index (NDVI) obtained from the Spot4/vegetation data

The operational Asian Dust Aerosol Model (ADAM)1 in Korea Meteorological Administration has been modified to the ADAM2 model to be used as an operational forecasting model all year round not only in Korea but also in the whole Asian domain (70-160°E and 5-60°N) using the routinely available World Meteorological Organization (WMO) surface reporting data and the Spot/vegetation Normalized Difference Vegetation Index (NDVI) data for the period of 9 years from 1998 to 2006. The 3-hourly reporting WMO surface data in the Asian domain have been used to re-delineate the Asian dust source region and to determine the temporal variation of the threshold wind speed for the dust rise. The dust emission reduction factor due to vegetation in different surface soil-type regions (Gobi, sand, loess, and mixed soil) has been determined with the use of NDVI data. It is found that the threshold wind speed for the dust rise varies significantly with time (minimum in summer and maximum in winter) and surface soil types with the highest threshold wind speed of 8.0 m s−1 in the Gobi region and the lowest value of 6.0 m s−1 in the loess region. The statistical analysis of the spot/vegetation NDVI data enables to determine the emission reduction factor due to vegetation with the free NDVI value that is the NDVI value without the effect of vegetation and the upper limit value of NDVI for the dust rise in different soil-type regions. The modified ADAM2 model has been implemented to simulate two Asian dust events observed in Korea for the periods from 31 March to 2 April 2007 (a spring dust event) and from 29 to 31 December 2007 (a winter dust event) when the observed PM10 concentration at some monitoring sites in the source region exceeds 9,000 μg m−3. It is found that ADAM2 model successfully simulates the observed high dust concentrations of more than 8,000 μg m−3 in the dust source region and 600 μg m−3 in the downstream region of Korea. This suggests that ADAM2 has a great potential for the use of an operational Asian dust forecast model in the Asian domain.

Direct shortwave radiative forcing of the Asian dust aerosol on dust emission

The physical processes of the feedback mechanism of direct shortwave radiative forcing of the Asian dust aerosol on dust emission has been examined using simulated results with the coupled (with dust shortwave radiative forcing) and the non-coupled model (without dust shortwave radiative forcing) based on the MM5 model and the Asian Dust Aerosol Model on 19 March 2002. The results indicate that a significant dust emission reduction occurs in the high dust concentration (HDC) region of the dust source region whereas an enhanced dust emission appears in the downstream of the dust source region. It is found that Asian dust aerosols raised during the daytime by the strong surface wind cause negative shortwave radiative flux near the surface, which in turn reduces the sensible heat flux causing the cooling of the air, thereby enhancing stable stratification. The dynamic adjustment of the negative radiative flux of the dust induces a positive pressure anomaly over the HDC region and a negative pressure anomaly toward the synoptic low pressure center, resulting in a dipole shape of pressure anomaly field near the surface. The associated secondary circulation of this pressure anomaly together with the reduction of turbulent intensity due to the reduced sensible heat flux reduces the low-level wind speed thereby reducing dust emission in the upstream of the HDC region of the dust source region (Region I), while enhancing the low-level wind speed in the downstream region (Region II), which in turn enhances dust emission. This enhanced dust emission is smaller than the emission reduction in the upstream, resulting in overall dust emission reduction during the daytime.

Simulation of dust aerosol and its regional feedbacks over East Asia using a regional climate model

Abstract. The ICTP regional climate model (RegCM3) coupled with a desert dust aerosol model is used to simulate the net radiative forcing (short-wave and long-wave) and related climate effects of dust aerosols over East Asia. Two sets of experiments are completed and intercompared, one without (Exp. 1) and one with (Exp. 2) the radiative effects of dust aerosols. The experiments encompass the main dust producing months, February through May, for 10 years (1997–2006), and the simulation results are evaluated against ground station and satellite data. The model captures the basic observed climatology over the area of interest. The spatial and temporal variations of near surface concentration, mass load, optical depth and emission of dust aerosols from the main source regions are reproduced by model. The main model deficiency is an overestimate of dust amounts over the source regions and an underestimate downwind of these source areas, which indicates an underestimate of dust dispersal. Over the desert source regions, the net TOA radiative forcing is positive, while it is small over the other regions as a result of high surface albedo values which reduce the short-wave radiative forcing. The net surface radiative fluxes are decreased by dust and this causes a surface cooling locally up to −1°C. The inclusion of net (short-wave and long-wave) dust radiative forcing leads to a reduction of dust emission in the East Asia source regions, which is mainly caused by an increase in local stability and a corresponding decrease in dust lifting. Our results indicate that dust effects should be included in the assessment of climate change over East Asia.

Effect of moisture on fine dust emission from tillage operations on agricultural soils

AbstractTillage is an important cause of release of particulate matter (PM) from soils. Measurements in Europe indicate that emission of dust by tillage operations is many times higher than by natural wind erosion. In Europe there are two periods when most tillage operations are carried out – in spring and in late summer. These operations are carried out under different soil moisture conditions. In spring soil moisture is close to field capacity and the surface soil dries mainly by evaporation. At this surface a dry layer is established, which is only few centimetres thick and impedes further evaporation. A different situation occurs in late summer, when the crops have depleted the soil water in the root zone. In this case the soils are dried‐up to a depth of some decametres. Tillage operations differ in depth and intensity, ranging from few centimetres of mixing at seedbed preparations to a few decametres of turning by ploughing. Hence, tillage‐related emissions are the combined result of vertical soil moisture distribution and depth and intensity of tillage operations.The objective of our study is to determine the influence of soil moisture on the particulate matter emission of soils subjected to mechanical disturbance, particularly tillage. Because the emission is a result of many variables that cannot be controlled in field experiments, we followed a stepwise analysis of the main influencing factors. First, we used a wind tunnel as a cross‐flow gravitational separator to investigate the relation between soil type, soil moisture and fine dust emission. Twelve soils of different texture were investigated with regard to their water content within a range from 0 to 40 per cent mass. The results show that soils can emit dust over a certain range of moisture, but even a small increase in soil moisture causes a distinct reduction of dust emission. The threshold water content for fine dust emission of soils was between 2 and 5 per cent mass for sandy soils, 5–10 per cent mass for silty soils, about 30 per cent mass for the clayey soils and 25–45 per cent mass for organic soils.The wind‐tunnel results were used to calculate the PM10 emission potential of a sandy soil in spring and late summer for a tillage depth of 20 cm by taking the measured vertical soil moisture profiles at these times into consideration. In spring only the upper 2·5 cm was dry enough to emit PM10, whereas in summer the soil was desiccated to the entire tillage depth. The calculated PM10 emission potential resulted in 13·4 g m−2 for the soil moisture conditions in spring and 76·8 g m−2 in summer. Finally, field measurements of the PM10 emission were made when ploughing the soil on both occasions. Modelling the measured data with the Lagrangian dispersion model GRAL resulted in PM10 emissions of 0·12 g m−2 for ploughing under the conditions in spring and 1·05 g m−2 in summer.Our results show the importance of the vertical soil moisture profile on the PM emission of soils. Therefore, the emission factors resulting from field operations should preferably be related to the affected amount/volume of a soil that is dry enough to emit PM rather than to the affected area. This is confirmed by the good correlation between the proportions of affected soil to the measured emissions. Our findings show that the differences between results obtained from laboratory methods and field measurements need further clarification. Copyright © 2008 John Wiley & Sons, Ltd.

Effect of Direct Radiative Forcing of Asian Dust on the Meteorological Fields in East Asia during an Asian Dust Event Period

Abstract Coupled and noncoupled models in a grid of 60 × 60 km2 in the eastern Asian domain have been employed to examine the effect of the direct radiative forcing of the Asian dust aerosol on meteorological fields for an intense Asian dust event observed in eastern Asia on 18–23 March 2002. The coupled model consists of the modified fifth-generation Pennsylvania State University–National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) with direct radiative forcing of the Asian dust aerosol through the NCAR Column Radiation Model and the Asian Dust Aerosol Model. The noncoupled model is MM5 without the direct radiative forcing of the Asian dust aerosol. The results indicate that the radiative cooling of the dust aerosol over the high-dust-concentration (HDC) region induces sinking motion and positive pressure perturbation near the surface, whereas the radiative warming of the aerosol near the top of the HDC layer induces rising motion and negative pressure perturbation, thereby enhancing the stable stratification in the dust layer. The induced positive pressure perturbation near the surface causes a dipole shape of the pressure perturbation field by forming a negative pressure perturbation toward the low pressure center downstream near the surface. This negative pressure perturbation is so deep and wide that the perturbation of the meteorological fields extends in the wide and deep regions away from the HDC region. The associated secondary circulation of this pressure perturbation reduces the low-level wind speed in the upstream HDC region but strengthens the downstream wind speed, resulting in reduction of dust emission in the upstream source region and downstream enhancement. Some of the dust aerosols lifted to the higher level by the synoptic rising motion are transported to the downstream direction more quickly with the upper-level strong wind, resulting in a bent-over shape of dust cloud in the downstream region with a maximum concentration near the surface and a secondary maximum in the upper level. The radiative flux convergence between these maximum dust layers produces a warm layer, thereby further enhancing the stable stratification.

Dust Emission and Efficiency of Local Exhaust Ventilation During Cast Iron Grinding

A method of determining dust emission and efficiency of its removal by means of local exhaust ventilation from machinery has been described. It complies with Standard No. EN 1093-3:1996 (European Committee for Standardization, 1996) and consists in determining air pollution concentra-tions in the measurement duct used for air removal from the chamber incorporating devices to be tested. The air volume stream that is pumped is measured at the same time.Test results are presented for dust emission and the efficiency of local exhaust ventilation for cast iron grinding by means of manual power tools and a bench-sander. It has been found that application of local exhaust ventilation contributes to a significant reduction of dust emission with efficiency greater than 90%.

The role of dust in climate changes today, at the last glacial maximum and in the future

Natural mineral aerosol (dust) is an active component of the climate system and plays multiple roles in mediating physical and biogeochemical exchanges between the atmosphere, land surface and ocean. Changes in the amount of dust in the atmosphere are caused both by changes in climate (precipitation, wind strength, regional moisture balance) and changes in the extent of dust sources caused by either anthropogenic or climatically induced changes in vegetation cover. Models of the global dust cycle take into account the physical controls on dust deflation from prescribed source areas (based largely on soil wetness and vegetation cover thresholds), dust transport within the atmospheric column, and dust deposition through sedimentation and scavenging by precipitation. These models successfully reproduce the first-order spatial and temporal patterns in atmospheric dust loading under modern conditions. Atmospheric dust loading was as much as an order-of-magnitude larger than today during the last glacial maximum (LGM). While the observed increase in emissions from northern Africa can be explained solely in terms of climate changes (colder, drier and windier glacial climates), increased emissions from other regions appear to have been largely a response to climatically induced changes in vegetation cover and hence in the extent of dust source areas. Model experiments suggest that the increased dust loading in tropical regions had an effect on radiative forcing comparable to that of low glacial CO 2 levels. Changes in land-use are already increasing the dust loading of the atmosphere. However, simulations show that anthropogenically forced climate changes substantially reduce the extent and productivity of natural dust sources. Positive feedbacks initiated by a reduction of dust emissions from natural source areas on both radiative forcing and atmospheric CO 2 could substantially mitigate the impacts of land-use changes, and need to be considered in climate change assessments.

98/02475 Reduction of dust emissions at coking plants : Stefanenko, V. T. et al. Koks Khim., 1997, (8), 25–30. (In Russian)

98/02475 Reduction of dust emissions at coking plants : Stefanenko, V. T. et al. Koks Khim., 1997, (8), 25–30. (In Russian)

Physico-chemical principles controlling the emission of dust from coal stockpiles

This paper describes the construction of an ‘environmental’ wind tunnel which enabled measurements of dust lift off as a function of such variables as wind velocity, particle size and moisture content to be performed under conditions of constant temperature and humidity. Aspects of coal-related properties were also investigated. All coals tested showed a strong response in reduction of dust emission with increasing total moisture content. Each coal exhibited a critical moisture content above which no emission occurred. Extensive studies were made of the effectiveness of chemical reagents in preventing dust emissions. Compounds intended to form hardened crusts on the stockpile surface, or to bind the top layer of particles, as in road base construction, were effective but at high cost. So-called agglomerating reagents were found to be ineffective for dust control.

A Laboratory Pilot Study to Investigate the Feasibility of Localized Electrostatic Precipitation for Dust Control in Industrial Workplaces

Abstract A system based on electrostatic dust deposition has been designed for the reduction of dust emissions from industrial process. This article presents details of the working principle and design of such a system as applied to a commercial textile winding rig and reports the results of measurements carried out to assess its efficacy. These have included comparison of the integrated dust concentration in the breathing zone of a dummy operative with and without the dust control unit in operation and measurement of the airborne dust concentration released from the unit when operational access is required. The relative merits of the electrostatically-based system are compared to those of conventional ventilation systems in terms of cost and operational constraints. It is suggested that the potential for high efficiency and low costs associated with the systems along the lines of the prototype tested here may constitute a cost-effective practical alternative or supplement to conventional ventilation.

Operation of a ventilation system for the cast house of a 5000-m3 blast furnace

The authors discuss the ventilation system of the 5000-m/sup 3/ blast furnace No. 9 at ''Krivorozhstal'' which has been in use since the end of 1974. To create optimum sanitary-hygienic conditions and to localize harmful emissions, the furnace is equipped with electric gas-cleaning equipment to clean air sucked from the stockhouse and cast house, and another wet-type system to clean the blast-furnace gas. They discuss ways in which this system has been made as efficient as possible. Tests of electrostatic precipitators ''on air'' made it possible to develop a stable operating regime for the power supply units for different values of the voltampere characteristics. During the study the authors also determined the chemical composition of the gas-air mixture removed from a charging apparatus installed in 1980 and devised a system to remove gases from the new apparatus in order to localize them. Overall, the work has produced reliable long-term operation of the exhausters and the reduction of dust emission into the atmosphere.