A pugmill or pug mill is a machine in which clay or other materials are mixed into a plastic state or a similar machine for the

trituration Trituration (Latin, ''grinding'') is the name of several different methods used to process materials. In one sense, it is a form of comminution (reducing the particle size of a substance). In another sense, it is the production of a homogeneous pow ...

of ore. Industrial applications are found in

pottery Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and por ...

brick A brick is a type of block used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a block composed of dried clay, but is now also used informally to denote other chemically cured cons ...

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mix ...

and some parts of the

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

and

asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...

mixing processes. A pugmill may be a fast continuous mixer. A continuous pugmill can achieve a thoroughly mixed, homogeneous mixture in a few seconds, and the right machines can be matched to the right application by taking into account the factors of agitation, drive assembly, inlet, discharge, cost and maintenance. Mixing materials at optimum moisture content requires the forced mixing action of the pugmill paddles, while soupy materials might be mixed in a drum mixer. A typical pugmill consists of a horizontal boxlike chamber with a top inlet and a bottom discharge at the other end, 2 shafts with opposing paddles, and a drive assembly. Some of the factors affecting mixing and residence time are the number and the size of the paddles, paddle swing arc, overlap of left and right swing arc, size of mixing chamber, length of pugmill floor, and material being mixed.

Common construction and industrial uses

Road Base - Dense well-graded aggregate, uniformly mixed, wetted, and densely compacted for building the foundation under a pavement. Lime Addition to asphalt – Lime may be added to the cold feed of an asphalt plant to strengthen the binding properties of the asphalt. Flyash Conditioning – Wetting

fly ash Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK) plurale tantum: coal combustion residuals (CCRs)is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired ...

in a pugmill to stabilize the ash so that it won’t create dust. Some flyashes have cementitious properties when wetted and can be used to stabilize other materials. Waste stabilization – various waste streams are remediated with pugmills forcing the mixing of the wastes with remediation agents.

Roller-compacted concrete Roller-compacted concrete (RCC) or rolled concrete (rollcrete) is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Po ...

– (RCC) or rolled concrete is a special blend of concrete that has the same ingredients as conventional concrete but in different ratios. It has cement, water, and aggregates, but RCC is much drier and essentially has no slump. RCC is placed in a manner similar to paving, often by dump trucks or conveyors, spread by bulldozers or special modified asphalt pavers. After placement it is compacted by vibratory rollers. The “stiff” nature of RCC may require a paddle type pugmill to force the materials to mix completely and discharge easily.

Ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...

s pug mills, or commonly just "pugs", are not used to grind or mix, rather they extrude clay bodies prior to shaping processes. Some can be fitted with a vacuum system that ensures the extruded clay bodies have no entrapped air. According to the 1913 edition of

Webster's Dictionary ''Webster's Dictionary'' is any of the English language dictionaries edited in the early 19th century by American lexicographer Noah Webster (1758–1843), as well as numerous related or unrelated dictionaries that have adopted the Webster's n ...

, a clay pug mill typically consists of an upright shaft armed with projecting knives, which is caused to revolve in a hollow cylinder, tub, or vat, in which the clay body is placed. Pugmills that run intermittently are used in the

kaolin Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...

mining industry to mix certain grades of

clay with water.

References

External links

{{Commons category, Pug mills
Pugmill mixing explanationPugmill Mixer Selection GuideWedging
a way to manually remove air bubbles from clay Tools Industrial processes Ceramic engineering Pavement engineering Materials science

Common construction and industrial uses

See also

References

External links