A conical mill (or conical screen mill) is a machine used to reduce the size of material in a uniform manner. It is an alternative to the
hammermill
A hammer mill is a mill whose purpose is to shred or crush aggregate material into smaller pieces by the repeated blows of little hammers. These machines have numerous industrial applications, including:
* Ethanol plants (grains)
* A farm mac ...
or other forms of
grinding mills
A mill is a device, often a structure, machine or kitchen appliance, that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many differe ...
. As the name implies, the conical mill varies in diameter from where the feed enters to where the product exits.
The conical mill operates by having the product being fed into the mill by gravity or vacuum. A rotating impeller forces the material outward to a conical screen surface, where it is sized and passed through the openings in the screen. Once finished, the product simply drops through the milling chamber to a receptacle underneath.
Conical mills come in a variety of sizes from tabletop lab models to full-size high-capacity machines for use in processing large quantities of material, and the impeller and screen can be customized for each individual use. The machines can be used not only to reduce the size of particles, but also for deagglomeration, sieving, dispersion, and mixing.
The applications for a conical mill are varied, but trend towards use in the food, cosmetic, chemical, and pharmaceutical industries:
*Reclaiming broken pharmaceutical tablets by grinding them back into powder for re-forming.
*Sizing wet granulated particles before drying, and sizing dry granulated particles after they've dried before tabletting.
*Delumping dry
detergent
A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are m ...
during production
*Dispersing
pearl
A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle) of a living shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium carb ...
into
blush and
face powder
Face powder is a cosmetic product applied to the face to serve different functions, typically to beautify the face. Originating from ancient Egypt, face powder has had different social uses across cultures and in modern times, it is typically u ...
*Deagglomerating dried fruits such as
raisin
A raisin is a dried grape. Raisins are produced in many regions of the world and may be eaten raw or used in cooking, baking, and brewing. In the United Kingdom, Ireland, New Zealand, and Australia, the word ''raisin'' is reserved for the ...
s or
cranberries
Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus ''Oxycoccus'' of the genus ''Vaccinium''. In Britain, cranberry may refer to the native species ''Vaccinium oxycoccos'', while in North America, cranberry m ...
.
*Creating
breadcrumbs
Bread crumbs or breadcrumbs (regional variants including breading and crispies) consist of crumbled bread of various dryness, sometimes with seasonings added, used for breading or crumbing foods, topping casseroles, stuffing poultry, thickeni ...
from scraps
The conical mill has some marked advantages over the hammermill, especially in the pharmaceutical industry: low noise, heat and dust, a more uniform particle size, flexibility in design, and higher capacity.
The concept of the conical mill was created in 1976 by the engineers of Quadro Engineering, who remains the foremost manufacturer of conical mills. Conical mills are available in Ex- execution with a variety of sieves and impellers. The mill head can be mounted on a mobile lifter which allows for easy up and down movement for docking into containers, tablet presses and others. The mill head is dismounted from a lifter for easy cleaning.
Sources
Pharmaceutical Dosage Forms- Details the advantages of conical mills in pharmaceutical industries
Fexofenadine Composition and Process for Preparing- Describes how a conical mill works
*{{cite journal , author=Schenck LR, Plank RV , title=Impact milling of pharmaceutical agglomerates in the wet and dry states , journal=Int J Pharm , volume=348 , issue=1–2 , pages=18–26 , date=February 2008 , pmid=17804181 , doi=10.1016/j.ijpharm.2007.07.029 — study of a conical mill's ability to size wet and dry granulates
Grinding mills