a. Dust is a very fine particle size (submicron) that easy to airborne.
b. The National Ambient Air Quality Standard (NAAQS) have targeted PM 10 (- 10 micron particulate) because these very fine particle represent the most serious health hazard
c. Process and Fugitive Dust are regulated pollutants.
d. The creation of Dust in industry is an unavoidable results of operation, such as; Dumping, Crushing, screening, conveying, discharging etc.
DUST IN COAL MINING INDUSTRY
COAL HANDLING CHAIN
Mining - Charging - Hauling – Dumping – Crushing – Stockpiling – Barging - Transshipments
a. These Operation could be generate fine coal, resulting Dust emission.
b. The longer handling chain, the more prone to generate of fine coal (dust).
FACTORS OF COAL DUST OCCURS
a. COAL PROPERTIESCOAL PROPERTIES
b. HANDLING SYSTEMSHANDLING SYSTEMS
c. WEATHER / SEASONWEATHER SEASON
d. ACCESS OF WIND AND WIND SPEEDACCESS SPEED
HOW TO CONTROL DUST
a. Minimizing coal handlingMinimizing handling
b. Use a proper equipments for handlinghandling
c. Suppress Dust occurs during operation
DUST SUPPRESSANT
a. Dry collection systems
are very efficient, however, this technology is capital intensive, high maintenance, and applicable only to sources that can be enclosed.
b. Water Spray system
remains the most efficient and cost effective means of dust control for both process and fugitive dustfugitive dust
c. Chemical Agent
Have wide spread used in industries to suppress dust problemsuppress problem
WATER SPRAY SYSTEM
a. The affectivity of water spray systems are relied on the nozzle used to spray water.
b. There are several types of nozzle available which results different type of water sprays.
– V-nozzle
– Full cone nozzle
– Fogger nozzle
c. The efficiency of the water spray system has established the following facts :
– For a given spray nozzle, the collection efficiency for small du dust st particle increases as the pressure increases
– At a given pressure, the efficiency increases as the nozzle design is changed so as to produce smaller droplets. Thus the smaller
droplet is more effective in knocking the small dust particle ou out of the air.
The Aerodynamic of water droplet and small dust
WATER SPRAYS
ULTRASONIC DUST SUPPRESSANT SYSTEM
a. The system use water and compressed air to produce micron size droplet that are able to suppress respirable dust without adding any detectable moisture to the process.
b. Generally the system consist of two main part. These are as follows :
– Air compressor unit
– Spray headers with pipelines and pumping system
c. The Ultrasonic Atomizing system generates droplets averaging 10 micron in size and is capable of suppressing subsub-micron dust particles. (conventional spray system generate droplets in average of 600 micron)
NOZZLE DESIGN
a. The Ultrasonic Atomizing Nozzle takes the form of a whistle using compressed air which accelerates through a converge section and expand to a diverge section into a resonator chamber. This produce a powerful sonic shockwave.
b. Droplets produced by sonic atomization are small and relatively uniform in size, in the order of 10 micron, with a low mass and low forward velocity.
ARCH FOGGER SYSTEM
CHEMICAL AGENT
a. The usage of chemical agents have widely spread in many industries to suppress dust problem
b. These chemical agent generally consist of polymer as a binder agent and surfactant to reduce surface tension between water and coaltension coal
c. In General the type of chemical agent are fall into two types, i.e.
– Wetting type
– Coating type
Surfactant
a. Surfactant is able to reduce surface tension between coal and water, and increase wet ability of coalability coal
POLYMER EMULSION
a. The polymer emulsion is a fine particle binder, and forms a coating layer on the coal surface
