Rice Quarterly: Fresh approach to rice milling

by Emily Wilson
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Travelers to Japan, where the day starts with a bowl of rice for breakfast and ends with a glass of sake, the traditional rice wine, are awed by the wide variety of rice-based foods and beverages that the country boasts.

When it comes to food, Japanese consumers are highly discerning and especially so for rice, a staple that holds a special place in the nation’s culinary and cultural tradition. Japanese consumers place very high demands on the quality of their rice. Cooking characteristics, flavor and not least, freshness, are the crucial criteria that decide rice product purchases.

All of these aspects had to be taken into consideration by Chiba-Ken Shokuryo Co. Ltd., as it contemplated the construction of a completely new rice mill. Its existing rice mill had ceased to meet the current requirements in terms of modern, clean and safe food production. This prompted the company to conduct initial studies for a new facility with an annual capacity of 40,000 tonnes of brown rice.

Buhler was contracted to build the new mill, and was involved in planning from the initial project phase. Buhler said the requirements of Chiba-Ken Shokuryo were clearly defined: the new rice mill was to be Japan’s most up-to-date installation of its kind.

Gentle conveying technology

The Buhler project team knew that fresh approaches had to be taken to achieve this ambitious goal. As a result, working in close collaboration with Chiba-Ken Shokuryo, Buhler developed a plant concept entirely novel to the Japanese rice industry, based on a multi-level layout that significantly improves plant sanitation and product logistics compared with conventional rice mills in Japan.

An essential module in this concept is the RiceLift conveying system, a technology newly developed for handling Japanese rice. This pneumatic conveyor is characterized by its ability to handle the rice extremely gently, without creating any breakage or abrasion.

Two factors ensure this very gentle conveying action. On one hand, the conveying pipes are specially treated and have no seams. Their walls are smooth, and the rice is conveyed at a very low velocity through the piping. Second, the material feeders and dischargers are designed to prevent damage to the rice during pneumatic handling.

This technology allowed a plant layout to be designed with numerous benefits. The processing equipment is positioned for operation and maintenance and dust-free pneumatic conveying ensures sanitary production in clean machines.

Chiba-Ken Shokuryo contracted Buhler and it’s RiceLift technology three years after the first decision was made to build the new rice mill, after the rice processor saw the RiceLift technology in Buhler engineering laboratories in Uzwil and Braunschweig. The contract comprised all the project engineering work, including installation, start-up, and control engineering. It also covered the supply of most of the electro-mechanical equipment for reception, cleaning, weighing, materials handling, brown rice processing, and white rice blending.

New approaches to processing

The new Chiba-Ken Shokuryo rice mill employs a fresh approach not only to materials handling, but also processing technology. For the first time ever in the rice industry, combi-cleaners are now applied for removing impurities from the brown rice. At the same time, they split the stream of material into a low-density (light) and a high-density (heavy) fraction. Both fractions can be processed as required by their specific characteristics.

The cleaned and graded brown rice is then further processed into bright white rice by three separate processing lines. Their equipment includes the TopWhite and HighPoly whiteners and polishers that ensure particularly gentle treatment of rice. Another innovative solution was applied to separating the brokens fraction: a single large-capacity plansifter is sufficient to remove all the brokens from the white rice of all whitening lines. This reduces the required number of machines by two-thirds compared with conventional solutions, thereby decreasing energy consumption and the maintenance and cleaning requirements.

Fresh rice

To enable Chiba-Ken Shokuryo to permanently supply its customers with fresh rice, the new mill allows the rice blends to be customized just before shipping.

Accurate proportioning is crucial here, since the individual batches are often very small. A total of 27 Transflowtron flow balancers ensure accurate proportioning of the individual components. The blends are then held in intermediate storage in stainless steel bins before being fully automatically packaged. The rice is then ready to be shipped.

All plant sections, from reception to finished product blending, are integrated in a state-of-the-art control system, which controls, monitors, and logs the entire process. A total of 43 Tubex scales and Transflowtron flow balancers register the material streams relevant to the process. They also allow detailed statistics to be created of the material inventories in the storage bins.

Preparation of the project from contract signing to the start of installation work took about one year. After four more months, the mechanical and electrical equipment of the rice mill had been installed. This included not only the processing equipment, but also 150 storage bins, 600 meters of pneumatic RiceLift lines, and over 700 meters of chain conveyor.

The new rice mill achieved the capacity and quality parameters within a very short time, enabling Chiba-Ken Shokuryo to shut down its old plant before the scheduled date.

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