Developments In Flour Milling Equipment

by Teresa Acklin
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From components to complete systems, flour milling technology continues to advance.

   Flour milling has come a long way since the rollermill era began in the 19th century. Even though the basic principles remain unchanged, milling technology continues to advance to help millers reach their goal: providing high-quality flour as efficiently and profitably as possible.

   The technological advances apply to many individual aspects of the process, as well as to total milling systems. A look at some of the latest developments:

      Assuring mellow wheat

   The basis for successful flour milling is well-tempered, mellow wheat. Buhler Ltd., Uzwil, Switzerland, has developed a new Tri-Rotor Dampener, type MOZK, to achieve this goal.

   The grain enters the dampener at the feeding section, where water is added according to the target moisture level required. Both grain and water then enter the vortex mixing chamber.

   The Tri-Rotor Dampener's three medium- speed horizontal rotors create a loose, whirling stream. Because of the vortex movement of the loose grain/water/air mixture, an extremely thorough mixing occurs, which results in an equal distribution of up to 5% water to each and every grain.

   The dampener's loose whirling action keeps grain breakage and beeswing production from abrasion to an absolute minimum. The filling degree and retention time are controlled by an adjustable outlet slide gate.

   The Tri-Rotor Dampener is available in two sizes for wheat capacities of up to 24 tonnes per hour.

      Finishing efficiency

   A new bran finisher from Kice Industries, Inc., Wichita, Kansas, U.S. provides efficiency, ease of operation and dependability with increased capa-city. The enlarged model BF42 is designed to handle about 675 to 900 kilograms per hour for coarse bran or 900 to 2,200 kg per hour for fine bran using a standard 7.5 to 10 horsepower motor.

   Hexagonal screens mean bran particles are forced against the screen and encounter a bend in the surface. This design allows the particles to be turned, bounced and reimpacted to increase separation efficiency.

   The screen “burrs” are on the inside for greater screen life and abrasion on the bran. Both screens also are easily rotated end-to-end to redistribute wear and essentially double screen life.

   Gasketed doors located on both sides can be opened on hinges or removed completely for easy access to both screens. Hardware and construction are heavy-duty and sanitary. Rounded corners eliminate dead spots and infestation harbors, and epoxy coating provides a smooth, clean finish. The units also can be suspended from overhead supports to keep the floor unobstructed.

      Reducing and sifting in one step

   The VALEK, offered by Molino Mechanical Industry and Trade, Inc., Konya, Turkey, is designed to augment the milling process by increasing capacity and extraction while assuring flour quality. In Turkish, “vals” means rollermill and “elek” means plansifter; the patented machine's name reflects its combined reduction and sifting functions.

   The VALEK consists of a metal housing with three beaters and a cylindrical cast iron coat. About one-third of the coat contains teeth, with the remainder consisting of a perforated sheet.

   In its most common and effective application, the VALEK is placed between the first break and plansifter, although other configurations are possible and one or more of the machines can be placed in other break passages. Following the break, stocks enter the machine, where further reduction occurs through a centrifugal beating process against the teeth. The perforated sifter sheet allows finer particles to pass to the plansifter, while coarser stocks move to the next break. Extraction to the plansifter is about 50%.

   Use of the VALEK allows increased roll gaps, which reduces roller heat and equipment wear. The larger gaps also allow a greater volume to pass through the rollermill, increasing mill capacity by 20% to 30%.

   The VALEK can raise total extraction rates by 1% to 2%, while lowering ash content. The machine's beating process enhances bran separation, and tests indicate ash content is reduced at virtually all rates of extraction.

      Milling with flexibility

   A flexible, complete milling system with a capacity of up to 24 tonnes per day is offered by Ocrim, S.p.A., Cremona, Italy. The PKF 424 fixed milling unit is designed to meet the needs of a variety of milling interests, from small entrepreneurs to strategic users.

   The unit, which weighs 15 tonnes and measures 65 cubic meters, can grind wheat and rye, or maize with a few modifications. System equipment includes a scourer, separator and dry stoner, as well as conditioning bins that can temper grain in about two hours.

   The mill section consists of eight passages and five turbo-sifters. The grinding rolls are in centrifuged casting measuring 250 by 325 millimeters, and brushes or scrapers ensure clean roll surfaces. The unit includes the same interlocking electric controls found in larger mills.

   The mill uses two tubular screw conveyors for discharge, one for flour and one for bran. The mill can process two types of flour, which is bagged after processing, and one by- product.

   The system requires 92 kilowatts installed power and is relatively easy to deliver and install; the unit arrives on a flat bed truck, and the only structural requirement is a level floor.

   Seven of the PKF 424 units are in operation worldwide, including two in Russia. Development of a larger version of the mill, with a daily capacity of up to 50 tonnes, is expected to be completed by the end of 1994.

      Original name, new products

   Prokop Milling Machines, Pardubice, the Czech Republic, will celebrate its 125th anniversary in 1995. Although the name Prokop ceased to exist after nationalization of the industry in 1946, flour and feed milling equipment continued to be made and supplied around the world.

   The Prokop name was resurrected about two years ago in the wake of reforms to privatize the Czech economy. Since then, the company has supplied about 35 flour mills to plants in the Czech and Slovak republics, Poland, Ukraine, other eastern European countries and former Soviet Union republics.

   Recent product developments include a new semolina purifier; square plansifters that increase output by 20%; and an in-line monitoring system with scales. Prokop also developed a complete continuous tempering system that automatically measures moisture content, temperature and hectoliter weight to control dampening.

   Prokop has developed a line of mini-mills, the PMM1 through PMM4 series, with capacities ranging from 10 tonnes to 50 tonnes per 24 hours. In 1995, the company plans to introduce the PMM5 mini-mill, which will have a capacity of 100 tonnes. Also in 1995, Prokop is developing new recirculating-air grain cleaning equipment.

   Prokop provides a complete line of milling equipment, from wheat intake, storage and pre-cleaning machines to flour packaging and bulk flour transportation equipment. The company also supplies a full range of engineering, design and training services, as well as tools, fixtures and spare parts.

      Longer-lasting milling rolls

   At the heart of any rollermill are the rolls themselves, and Satake, U.K., Stockport, U.K., for a number of years has been testing a new type of alloyed cast iron for its fluted rolls. This unique alloy is basically a white chromium iron developed to combat the specific wear problems associated with fluted cereal milling rolls.

   Marketed under the registered trademark of MITAK, the alloy exhibits far greater wear resistance than conventional chilled cast iron rolls. Long term trials have shown that the MITAK roll on first break applications can give more than twice the life between refluting than good quality chilled cast iron rolls.