Accelerated silicosis. A form of silicosis resulting from exposure to high concentrations of crystalline silica and developing 5–10 years after the initial exposure. While accelerated silicosis presents with the nodular characteristics that typify chronic silicosis, accelerated silicosis generally progresses more rapidly than chronic silicosis.

Access road. A road that is generally used for utility or maintenance purposes. This is usually a secondary road, which is smaller in design than a haul road. An access road is not normally used for moving ore between the pit and crusher locations.

Acute silicosis. A form of silicosis resulting from exposure to unusually high concentrations of respirable crystalline silica dust. Symptoms develop within a few weeks to 4–5 years after the initial exposure. In contrast to the more common chronic and accelerated forms of silicosis, acute silicosis involves a flooding of the alveolar region of the lungs with abnormal fluid containing fats and proteins, which gives rise to an alternative term for the disease—silicoproteinosis. Acute silicosis is uniformly fatal, often within several months of diagnosis.

Aerodynamic diameter. The diameter of a spherical particle that has a density of 62.4 pounds per feet cubed (lbs/ft3) (the standard density of water) and the same settling velocity as that of the particle in question. Although particles have irregular shapes, this is an expression of a given particle’s behavior as if it were a perfect sphere.

Agglomeration. The act or process of gathering into a mass.

Air atomizing. Mixing compressed air with a liquid to break up the liquid into a controlled droplet size.

Airborne dust prevention. Control measures taken to prevent dust from becoming airborne. Airborne dust suppression. Control measures taken to suppress dust after it has become airborne.
Air quantity. The amount of air used in ventilating a process, which is a combination of the air velocity or speed and the area of the duct, measured in cubic feet of air per minute (cfm).

Air to cloth ratio. In dust collection systems, a measure of the volume of gas per minute per unit area of the bag collecting dust.

Air velocity. The speed of air traveling in an area or duct measured in feet per minute (ft/min). Alveoli. Tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place. Annulus. The open area of the drill hole between the drill steel and the wall of the drill hole.

Articulated positioner. A mechanical device that transfers product to a loading spout while also moving the loading spout from side to side as well as forward and back to ensure proper positioning of the spout discharge.

Asbestosis. Pulmonary fibrosis (scarring of the lungs) caused by the inhalation of asbestos fibers.

Autogenous. Size reduction of materials accomplished by impact and compressive grinding of the material by large units of the material itself—i.e., no balls or rods are employed.

Axial-flow fan. A fan that moves air in a direction parallel to the axis of the rotation of the fan. Axial-flow fan types include propeller, tubeaxial, vaneaxial, and two-stage axial-flow.

Backflushing. The action of reversing the flow of air or water in a system to remove contaminants from a filter.

Bagging. Loading of product into some type of paper, cloth, or plastic bag to be shipped/delivered to customers.

Baghouse collector. In dust collection systems, a type of collector that captures the particulate in an air stream by forcing the air through filter bags.

Bag perforations. Vent holes integrated into bags of product to allow air to escape rapidly and to reduce bag failures (e.g., rupturing or exploding).

Bag valve. Sleeve placed inside 50- to 100-lb product bags to allow for the insertion of the fill nozzle during bag loading and the sealing of the bag when loading is completed.

Bailing airflow. Compressed air blown down the drill stem through the bit in order to flush the cuttings out of the hole.

Blowback. Product spewing out from the bag valve during bag filling.

Bonding strength. The ability of material to adhere to itself and to the material to which it is applied.

California Bearing Ratio. A test that provides results as a ratio from the comparison of the bearing capacity of a material to the bearing capacity of a well-graded crushed stone.

Capture velocity. A measure of the airflow necessary to seize dust released at a source and then pull this dust-laden air into a (capturing) hood. Capture velocity is measured in feet per minute (ft/min).

Capturing hood. A hood positioned as close to a dust source as possible to capture the dust-laden air and pull it into an exhaust ventilation system.

Carryback. Material that sticks or clings to a conveyor belt after passing over the head pulley.

Cartridge collector. In dust collection systems, a type of collector that captures particulate from an air stream by forcing the air through filter elements, which are arranged in a pleated configuration.

Centrifugal collector. In dust collection systems, a device that separates particulate from the air by centrifugal force. Also called a cyclone.

Centrifugal fan. A fan in which the airflow is drawn into the rotating impeller and discharged radially from the fan blade into the housing. Centrifugal fans include radial, backward, and forward blade types.

Chimney effect. The behavior of heated air or gas rising in a vertical passage or area, as in a chimney, due to its lower density compared to the surrounding air or gas.

Chronic silicosis. A slowly progressive, nodular form of silicosis that typically develops after 10–30 years of exposures to respirable crystalline silica dust.

Coanda effect. The tendency of a moving fluid to be attracted to a nearby surface.

Collaring. The preliminary step in drilling, which forms the beginning of a drill hole, or collar. Contact angle. The angle at which a liquid meets a solid surface.
Control efficiency. A standard of measure, usually expressed as a percentage, used to compare the results of two or more outcomes.

Cure. The hardening of a chemical additive and base material.

Cuttings. Material that is produced during the drilling process. Cuttings are usually a fine-sized material.

Cyclone. A conical device that uses centrifugal force to separate large- and small-diameter particles.

Depth loading. In dust collection systems, a method of collecting particulate on a fabric by maintaining a filter cake on the fabric to optimize collection efficiency. When depth loading is used on a particular fabric, dust is intentionally allowed to penetrate into the fabric to form a layer of dust on the bag.

Diffusion. The spread of dust particles from high concentration areas to lower concentration areas. Many times, this is achieved in ventilation systems by dust-laden air being mixed with clean, dust-free air.

Dorr-Oliver cyclone. A compliant sampling device approved by the Mine Safety and Health Administration (MSHA) designed to separate respirable-sized particles from a dust-laden air stream.

Drifter drill. A drill used in underground mining to drill horizontal holes.

Drill deck (drill table). A deck or table on the drill located 2–3 feet above the ground surface and adjacent to the drill operator’s cab. This deck is used by the operator to gain access to the drill rods when needed to add more rods or to change drill bits.

Drill rods. Metal rods, also called “steels,” used to connect the rotary head to the drill bit as drilling proceeds through the ground.

Dual-nozzle bagging system. A type of fill nozzle for filling 50- to 100-lb bags of product where the inner nozzle is used for filling and the outer nozzle is used to exhaust excess pressure from the bag.

Dust. Small solid particles, often created by the breaking up of larger particles. Dust collector. An air cleaning device used to remove air-entrained particles. Dust collector airflow. The quantity of air that flows through a dust collector.
Dust collector airflow to bailing airflow ratio. A ratio of dust collector airflow and bailing airflow, mathematically represented as the dust collector airflow divided by the bailing airflow.

Dust suppressants. Chemicals or substances applied to a surface to prevent airborne dust from being released from the surface.

Elastic limit. The maximum stress that can be applied to a material without causing permanent deformation.

Electrostatic charge. The physical electrical property of a dust particle that will cause it to experience a force, either attracting or opposing, from another charged electrical component or device.

Electrostatic precipitator. A particulate control device that uses electrical forces to move particles from the air stream to collection plates.

Elutriation. The process of separating lighter from heavier particles by flow between horizontal plates.

Enclosing hood. A hood that either partially or totally encloses an area to capture the dust source or dust-laden air and prevent it from flowing out into a mine or plant environment where it could contaminate workers.

Entrainment. The process of particles being captured and carried with the airflow.

Epitropic fiber. A fiber whose surface includes embedded particles designed to modify the fiber properties, typically electrical conductivity. Commonly used epitropic fiber materials include carbon, graphite, and stainless steel.

Exhaust. In ventilation systems, to directionally move air using an energy source (typically a fan).

Exhaust ventilation system. An engineered system designed to use negative pressure to draw air through a network of openings via a fan.

Filter cake. A solid mass of substances remaining on a filter which becomes thicker as particulate matter is retained on the filter media. This mass then improves filtration while increasing flow resistance/pressure and decreasing airflow through the filter media. Over time, this filter cake should be removed using some type of mechanical or air pulse system.

Flexible intermediate bulk containers (FIBCs). Large product containers, normally 1,000 lbs and greater when filled, used to ship bulk material to customers. Also called “bulk bags,” “mini-bulk bags,” “semi-bulk bags,” and “big bags.”

Fogger spray. Compressed air and water forced through a nozzle to create a fogged-in area, resulting in a mist that aids in dust suppression.

Fugitive dust. Solid airborne particulate matter that escapes from any dust-generating source. Gradation. The distribution of different particle sizes in aggregate material.
Gravity separator. In ventilation systems, a large chamber where the velocity of the air stream is drastically reduced in order to facilitate the vertical drop of particles. Also called a “drop-out box.”

Haul road. A road used for hauling ore to and from pit and crusher locations at a surface mine. Hauling is generally conducted using large off-road haul trucks.

Hydraulic (airless) atomization. Controlling droplet size by forcing liquid through a known orifice diameter at a specific pressure.

Hydraulic flat fan nozzles. In wet spray systems, nozzles used to produce relatively large droplets over a wide range of flows and spray angles, normally used in narrow enclosed spaces.

Hydraulic full cone nozzles. In wet spray systems, nozzles used to produce a solid cone-shaped spray pattern with a round impact area that provides high velocity over a distance.

Hydraulic hollow cone nozzles. In wet spray systems, nozzles used to produce a circular ring spray pattern, typically producing smaller drops than other hydraulic nozzle types of the same flow rate.

Hydrogen embrittlement. A process by which metal (high-strength steel) can become brittle and fracture due to exposure to a hydrogen source.

Hygroscopic. The ability to absorb moisture from the air.

Impingement plate scrubber. A type of wet scrubber in which dust-laden air passes upward through openings in perforated plates, which hold a layer of water.

Induction. Airflow or product movement that creates sufficient momentum energy to pull additional surrounding dust-laden air into the airflow or product movement.

Inhalable dust. A fraction of airborne dust intended to represent those particles likely, when inhaled, to be deposited in the respiratory tract from the mouth and throat to the deep lung. The collection efficiency of an inhalable dust sampler varies by the aerodynamic diameter of the particles—to demonstrate, about 50 percent of 100-micrometer particles (but nearly 100 percent of particles less than 1 micrometer) are collected.

Inlet loading. In ventilation systems, the amount of dust traveling to the collector.

Intake air. In ventilation systems, the clean air supplied into an area or space to replace existing (contaminated) air.

Laminar. Sometimes referred to as streamline flow, the occurrence of air flowing in parallel paths with no disruptions between the paths.

Local exhaust ventilation (LEV). A system used to capture dust and remove it from a mine or plant environment. The concept is to capture dust-laden air, pull this air into an exhaust hood, transport the dust-laden air through ductwork to some type of dust collection system, and duct the dust-free air to some type of exhaust fan, which creates negative pressure, resulting in the airflow for the entire system.

Makeup air. In ventilation systems, the clean air necessary to supply a specific ventilation application (e.g., a local exhaust ventilation system).

Mechanical shaker collector. In dust collection systems, a type of collector that uses mechanical shaking to remove the excess dust cake from the collection media.

Mesothelioma. A lung disease that originates in the mesothelium—a thin layer of tissue lining most of the internal organs—attributed to occupational overexposure to asbestos fibers and certain other mineral fibers, such as erionite.

Musculoskeletal disorder (MSD). Health problems in the body’s muscles, joints, tendons, ligaments, and nerves. When work-related, these problems are caused by the work process or environment.

Open structure building design. A processing structure or building designed without exterior solid walls in an effort to lower respirable dust and noise levels.

Overhead Air Supply Island System (OASIS). A filtration system located over a worker at a stationary position to filter dust-laden air from the work environment and deliver a clean envelope of air down over the worker.

Palletizing. In the mineral processing industry, when bags of product, normally ranging in weight between 50 and 100 lbs, are loaded onto a pallet for shipment to customers.

Percussion drilling. Rock penetration through rotation and down-pressure with a pneumatic drill, which contains a piston that delivers hammer blows to the drill column or the drill bit to enhance the drilling effectiveness and rate.

Photo eye. A photoelectric sensor that detects a change in light intensity for the purposes of controlling or detecting something, such as the presence of ore on a conveyor or piece of machinery.

Pitot tube. A pressure-measuring instrument normally made out of two concentric metal tubes that can be used in conjunction with a manometer to measure the static pressure (SP), total pressure (TP), and velocity pressure (VP) due to airflow in the duct.

Protection factor. A numeric value comparing outside to inside dust concentrations. Examples of where protection factors apply include personal protective equipment and environmental enclosures.

Pulse jet collector. In dust collection systems, a type of collector that uses timed or pressure- induced blasts of compressed air to recondition filter bags by removing the filter cake.

Push-pull ventilation system. The technique of using an air jet (blowing system) directed toward a dust source and receiving hood (exhaust system) to capture and move dust-laden air into the hood.

Respirable crystalline silica. Particles smaller than 10 μm in aerodynamic diameter that, when airborne, can be inhaled deep into the lungs and cause serious health issues.

Respirable dust. A fraction of airborne dust intended to represent those particles likely to be deposited in the alveolar region of the lungs when inhaled. The collection efficiency of a respirable dust sampler varies by aerodynamic diameter of the particles—to demonstrate, only about 1 percent of 10-micrometer particles (but nearly 100 percent of particles less than 1 micrometer) are collected.

Reverse air collector. In dust collection systems, a type of collector that uses a traveling manifold to distribute low-pressure cleaning air to the filter bags for reconditioning.

Roof ventilators. Either axial or centrifugal fans placed on the roof of a building and used to pull air out of the structure and discharge it into the atmosphere.

“Rooster tail.” Product spewing from the fill nozzle and bag valve as the bag is ejected from the bag filling machine.

Rotary drilling. Penetration through rock and ore by a combination of rotation and high down- pressures on a column of drill pipe with a roller drill bit attached to its end.

Scarify. To break up or loosen the ground surface.

Semi-autogenous. Size reduction of materials accomplished by impact and compressive grinding of the material by large units of the material itself, with the use of balls or rods to provide additional crushing force.

Silicosis. A progressive and incurable lung disease that belongs to a group of lung disorders called the pneumoconioses. Silicosis is caused by repeated inhalation of respirable crystalline silica (e.g., quartz) dust.

Skirting. On conveyors, a horizontal extension of the loading chute used to contain ore and dust within the transfer point. On loading spouts, strips of belting or fabric installed on the spout discharge end, creating a physical seal with the product pile to reduce dust liberated during bulk loading.

Spoon. When material is being conveyed, a curved plate that helps steer the material in the desired direction.

Spray tower scrubber. A type of scrubber that employs water, which falls counter-current through a rising dust-laden air stream, to remove dust particles.

Spreader box. An implement used in road construction to spread road material (typically gravel or sand) in a uniform layer. The implement, commonly in the shape of a box, is attached to and moved by mobile equipment, such as a bulldozer.

Static pressure (SP). In ventilation systems, a measure of the pressure in a ventilation duct relative to the atmospheric pressure. Static pressure can be either a positive (expansion) or negative (contraction) value. Static pressure summed together with velocity pressure (VP) provides the total pressure (TP) for a duct in a ventilation system.

Stilling zone. An enlarged area beyond the transfer zone of a belt conveyor designed to slow the airflow and allow airborne dust to return to the ore being transported.

Stoper drill. A hand-operated drill typically used in underground mining to drill vertical holes overhead. Also referred to as a jackleg drill.

Sub. A short length (usually 2–3 ft) of drill collar assembly, made of the same drill steel material, which is placed between the drill bit and the drill steel.

Subbase. In road construction, the layer between the subgrade and the wearing surface.

Subgrade. In road construction, the underlying soil or rock that serves as the foundation for the road.

Surface loading. In dust collection systems, a method of collecting particulate on the surface of a fabric to create a dust cake.

Surfactants. Substances that, when dissolved in water, lower the surface tension of the water, allowing the water to “wet” the dust more easily.

Table bushing. A bushing used to seal the opening where the drill steel passes through the drill deck.

Tilt sensor. On bulk loading spouts, a vertically mounted sensor designed to prevent blockages during loading. As the product pile grows and moves the sensor off of vertical by a predetermined amount (e.g., 15 degrees), an electronic signal is transmitted to initiate the raising of the spout.

Total pressure (TP). In duct ventilation systems, the sum of static pressure (SP) and velocity pressure (VP).

Total structure ventilation system. The use of exhaust fans high on the outside walls or roof of a structure to bring in clean outside air at the base of a building, which sweeps up through the structure to clear dust-prone areas.

Tri-cone roller drill bit. A rotary drill bit with three roller cones. As the drill bit rotates, the roller cones, which have carbide components, roll against the bottom of the drill hole, causing the material to break into small particles. This type of drill bit requires high down-pressure on the drill bit.

Velocity pressure (VP). In ventilation systems, the pressure required to accelerate air from being at rest to a given velocity. Velocity pressure added to static pressure (SP) provides the total pressure (TP) in a duct.

Venturi eductor. In pneumatic conveying systems, a device that converts blower output into suction to entrain dust-laden air, product material, or both into the conveying line.

Venturi effect. A reduction in static pressure resulting from a liquid or gas flowing through a constricted space.

Venturi scrubber. A type of wet scrubber consisting of a venturi-shaped inlet and a separator.

Water cartridges. A plastic or polyvinyl chloride (PVC) bag filled with water and inserted into the blasthole along with the explosive, resulting in dust suppression during blasting.

Water separator sub. A short length of a drill collar assembly placed between the drill bit and the drill steel. A water separator sub uses inertia to remove the injected water from the bailing air prior to reaching the drill bit to prevent hydrogen embrittlement.

Wear liner. A hardened or otherwise extended-life sacrificial material used to prevent premature wear on mining equipment.

Wearing surface. The top layer of the road surface that is exposed to traffic.

Wet cyclone scrubber. A type of scrubber that uses centrifugal force to throw particles on the collector’s wetted walls.

Wet drilling. In surface drilling, the injection of water along with air to flush the cuttings out of the hole.

Wet scrubber. An air pollution control device used for particulate collection. Wet scrubbers employ water or another liquid as the collection media.

Wet spray systems. A system of water sprays used to wet fines so that each dust particle’s weight increases, thus decreasing the particle’s ability to become airborne.

Windrow. A long linear pile of material.