Current status and future of liquid coating

For liquid application, various technical principles and equipment are in development or already available. As a new technology, there are still many arguments on the issues such as carrier selection, reaction between ingredients, optimal droplet size distribution as well as proof of the sufficient operating accuracy. Take droplet size as an example. For homogenous distribution of the additives in the feed a high number of small droplets seems to be the best. But the mass of fine droplets is very low so that they follow more closely stream forces than mass forces. The consequence is the transport of the fine droplets with the air. Therefore optimization of the spray structure should not be neglected. After all, the utilization of liquid ingredients in a post treatment process opens a lot of new doors to the feed manufacturer. This can be seen in the following aspects. A. From an economic point of view there will be saving as the need for overdosing of micro-ingredients, some of which are quite expensive, will be eliminated. The range of micro-ingredient products available to the feed miller will be greater as the restraints of high temperature degradation are removed. Production flexibility will be increased as basic formulations are converted to customer-specific ones in an offline coating system. B. From an environmental point of view, micro-ingredients in liquid form are easier to handle. Many of the present micro-ingredients in powder form are hand dumped to avoid losses. Dust from these can be hazardous. C. Cross contamination has always been a problem facing the feed manufacturer. For example, trace elements of some antibiotics used in pig feed formulations may not under any circumstances be found in chicken feeds and if the traditional micro weighing system, transport and mixing system is used this is almost impossible to avoid. D. The design of future feed mills may also change as the use of liquid ingredients increases. Space requirements for micro weighing systems will be reduced. At the same time off-line coating systems, where basic formulations can be converted to customer-specific ones while outloading, will reduce the number of finished product bins. As liquid coating systems compared to micro weighing installations are considerably simpler and cheaper, i.e. in terms of transport, mixing, weighing equipment, bins etc, which are required for micro weighing, installation costs and capital investment will be reduced. The use of liquid coating system in a post thermal treatment process whilst still a relatively mew concept to most is undoubtedly something we will be seeing a lot more of in the future.