Application of Ball-Milling Technology for the Preparation of NanoPlant Fines

Qu Yuan Qu Lai Qu Shaozhong

The research and development of nanoplant fines proceed rather slowly, and the health foods of natural plants such as nanopollen and auricula, the rare medicinal plants such as ginseng, glossy ganoderma, pearls and cordyceps sinensis and the toxic medicinal plants such as strychnos nux-vomica are all in their development stage owing to the scientific and technical problems. In respect of science, articles on the application of nanoplants and what problem exactly can be solved with the nanoplant fines have appeared one and another. This article discusses the problem of technical application.

The multidimensional swinging nano-ball-milling technology and the multiplayer grading nano-ball-milling technology invented by Mr. Lv Qing and Mr. Qu Yuang have solved the problems encountered in the application of nanoplant fine preparation technique with the former having obtained a patent and the later being under examination for granting a patent.


?? Ball milling technology for the preparation of nanoplants

1 . Multidimensional swinging and high-energy nano-ball-milling technology

Multidimensional swinging and high-energy nano-ball-miller, as a closed high-energy milling machine and through the quick multidimensional swinging motion of its tank, is able to make the irregular motion of milling medium in the tank generate a tremendous impact force with increased impact times, prolong the motion trace, augment the impact energy and lessen the impact blind spots with its working efficiency increased several dozen times over the traditional ball millers, and the particles of broken substance reaching a nano-grade. Meanwhile, the homogeneous degree of particles can also be increased with the minimum diameter of particles standing at 10 nm. Using this equipment, Qinhuangdao Taiji Ring Nanoproducts Co., Ltd has succeeded in preparing nanofood (nanoteas and nanocoffee) and nano-Chinese medicine (paste), the application of which has been popularized (see Figure 1-2).


Figure 1 Multidimensional tank swinging trace (front view)


Figure 2 Multidimensional tank swinging trace (top view)

Apart from plants, this equipment can be widely used in the experience and production of nano-grade fines of organic and inorganic materials such as metals, non-metals, multi-alloys, mechanization alloys, animals, mines and medicinal materials (for the pulverization of inflammable and explosive materials, protective agents such as argon, nitrogen and carbon dioxide should be added).

2 . Multiplayer grading nano-ball-milling technology

Multiplayer grading nano-ball-miller, according to the movement principle of a rectifier's hand, is able to revolve repeatedly and quickly in double directions, increase the chance of trace variation of the medium, generate a high-energy impact and make the materials dash on the miller in motion and the fines continuously pulverized in the multi-chambers, multi-layers and the multi-diameter medium (changing gradually from large to small) during their being fed in the flow, and thus having been finally pulverized to over 10 nm.

This equipment is an open miller, can be operated with or without water, with materials fed and discharged continuously. It can be widely used to pulverize organic and inorganic materials such as animals, plants, mines, metals, ceramics and non- inflammable and non-explosive materials.

• Some problems in the preparation of nanoplant fines with ball milling

• Temperature. Because both the above two ball millers are high-energy millers and the plant fines are easy to be coked and carbonized in the quickly increasing temperature in the machines, the temperature is the first problem to be solved. For the closed miller, it can be cooled by adding fluid nitrogen, but as the purity of the fluid nitrogen is different to control, the plant is apt to be polluted and the production cost is rather high, so we have adopted cycling water cooling in a jacket in the tank to effectively control the temperature during the processing.

• Humidity. Plants usually have a water content of 5-10% to increase their toughness and elasticity. In order to increase their brittleness, it is necessary to remove the moisture, so we have adopted a method of drying the plants for 4-6 hours under 55 ? and then processed in the ball miller, and gained a better effect. If an example is made in a experimental equipment, the roots, stems, barks, leaves, flowers and fruits of the plants can be pounded to pieces (or crushed to rough fines with small miller) and then fed into the tank after drying. If fresh plants are adopted, they can be beaten first with traditional disintegrator, then made into size with high-energy ball miller and finally dried with spray. This method works well in the preparation of fresh green tea and cold tea.

• Stickiness. Some plants, such as prepared rhizome of rehmannia, medlar, Chinese dates , frankincense and myrrh, contain too much sugar or oil or colloid, which might stick onto the balls, the tank or palletized in the ball miller, and reduce the milling effect. For these kind of plants, if a method of deep cooling and milling is adopted, the temperature of the materials will increased after taking out from the refrigerator, and if fluid nitrogen is added, the plants will be polluted. For these reasons, we have adopted humid milling. In this method, the plants are crashed and water is added to form a kind of size, and then made with ball miller into nano-size, and finally dried with spay after having reached milling effect. This method have solved the problem of stickiness and also preserved the characteristics of these plants.

• Pollution. The ball milling technology, especially the high-energy milling is faced with a problem of plant pollution, and the problem will be more serious if steel balls are adopted and the plants are not cooled and temperature not reduced. We, therefore, have replaced the steel balls with zirconium balls and have the tank lined with zirconium oxide to minimize the pollution to the materials. The zirconium balls are usually replaced once half a year if milling plants, showing the pollution is rather low. Besides, the trace element zirconium exits in many health foods, benefits health, and is needed by human body to grow teeth and skeleton.

• Agglomeration. When the plants are milled into nano-size, the particles will have a large specific surface area with high energy and much electric load, and their hydrophily, are apt to obsorb water and pelletized. Meanwhile, most health foods are made to be plant drinks. Pelletized nanoplant fines are difficult to disperse when watered, apt to settle, and this will affect its appearance and taste. The methods to over come this shortage have become a commercial secret for many companies the world over, one of them is to add food-grade dispersing agent in the micro-grade materials before ball milling to modify their surface characteristics, remove their surface energy and static electricity and improve their dispersion. The dispersing agent can also increase the milling effects. Another method is to add food-grade modifier in the micro-grade materials before ball milling, modify the surface of nanoplant particles and increase their dispersion in the course of ball milling. After thus processed, whether watered with cold or hot water, the green tea will become immediately dark green, the black tea glow, and will not deposit.

• Granularity and evenness. Granularity, the diameter of the particles, is usually expressed by the average diameter, namely, the statistical average diameter value. How much is the best diameter of the particles of nanoplant fines? Through several years' research, we think that the average diameter should not less than 100 nm, and 120-180 nm is the best. In this range of diameter, not only the walls of plants are broken, the cells in them are broken as well, and the process of physical fining have been completed with the nutrition and medical component of the fines able to be sufficiently absorbed (except the plants to be used for the research of viruses). If pursuing completely for less than 100 nm, it would be dangerous to increase unstable factors, change the characteristics of the plants and generate side effects. The nanoplant processing is aimed at improving the absorption and it is too early to expect it to produce new modified materials.

Evenness means the distribution range of the particles. The more concentrated of the distribution, the more even the particles would be. The evenness of the fine particles prepared by ball milling is not well and therefore not ideal for producing strictly nano-modified materials such as metals. However it is best suitable to prepare nanoplant fines, because the nanoplant processing is not aimed at modification but at "preservation". Therefore, we are striving to control the particles at a range of 60-180 nm. The key point of the control is to shorten the milling time to the greatest degree. For this purpose, we have adopted a procedure named "three steps of nano-tea preparation" - first, crushed with traditional method, second, crushed with air flow (impact between materials, not polluted by iron), finally, the micro-grade materials are prepared into nano-fines with high-energy ball milling, thus greatly shortened the milling time and decreased the pollution.

Controlled in the first two steps (crush, screen, crush with air flow and screen again), the evenness can be achieved as expected.

?? Development and forecast of nanoplant ball milling technology

Plants contain a lot of such organic substances as protein, amino acid, vitamin, fibrin and trace elements, as swell as dozens of inorganic mineral elements and medical components, which are needed by human body and play an important role in health care and medical treatment. But study shows that if their walls are not broken, the proteins and medical components are difficult to be absorbed.

Among the physical crush technologies, the ball milling technology is welcomed by many people. However, the nano-fines preparation, especially in the field of nanoplant fine preparation, was confronted with challenges from many problems such as unevenness of particles, serious pollution and long time processing, which were once neglected. However after several years' hesitation and looking back now, it can be seen the nanoplant fine preparation technology is still a feasible one with its low costs and high efficiency.

The nanoplant fines prepared with the new multidimensional swinging and multi-layer grading ball milling technology are produced with pure physical method, and the plants themselves are not damaged, with their natural components and integrality preserved and no other components introduced.

Our practice has shown and will continue show that although Japan anticipated us in applying the nanotechnology to the Chinese medicines, we are the first to develop the high-energy nano-ball milling technology and apply it to the fields of plant and the Chinese medicines. This new milling technology and the nano-grade plant fines will certainly bring about new vitality to the relevant plant processing sectors, become a new growing point for the food, health food, cosmetic, and the Chinese medicine industry and serve the health of the people with its quick, high and long-time effective products of high solubility, absorption, adsorption and biological utilization.

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