Depending on types of fish feeds, sinking feeds can be made on both pelleting and extrusion systems. Pellet mill can only make fast sinking feeds; however, extruder offers more products characteristics from fast sinking, slow sinking, and floating. For example, milk fish feeds are still common to be made on pelleting lines thanks to advancement on pre-conditioning and post-conditioning technology.
IDAH’s contribution to extrusion technology
IDAH manufactured the first extruder in 1980s and established an extrusion research lab which comprises of two co-rotating twin screw extruders in 1996. The research lab was later to be expanded and grown to an ISO, HACCP and AIB certified food company. A food company which focuses on marketing textured soy protein, textured wheat protein and complete ranges of meat alternatives (vegetarian) products like burger patty, chicken nuggets, sausage and ham made out of TVP. By utilizing the extrusion facility there, IDAH has developed numerous specialized products in feed and food applications.
Research lab established in 1996
In 2007, IDAH invents ContraTwin screw extrusion technology which creates a new blueprint in extrusion for feed and food application. ContraTwin is a technology that optimizes the co-rotating twin screw extrusion technology for aquatic feeds production. VC2R drying technology joins in the line for the accurate moisture reduction and making ContraTwin together with VC2R the most advanced extrusion line for aquafeed production.
Extrusion process description for aquatic feeds
In a extrusion line, IDAH can offers complete process solutions and equipments including mixer, hammer mill, pulverizer, extruder, dryer, coater, sieve, bagging machines and automation control systems.
Raw material intake system consisting of tip hopper, mechanical conveyors and elevators into storage bins. Raw material is sieved to remove any impurity and irons. Raw material, for example, for animal feeds are soy bean meal, corn meal or other grain sources. For aquatic feeds, material can be fish meal or flour.
Pre-grind systems is a size reduction process for raw materials that contains large particulates or grains by hammer mills. Pre-ground material is conveyed to storage bins. (Location for this grinding system can be designed to suit the process flow that follows)
Storage bins for raw materials
Formula batch dosing system: Weighing hoppers to blend finished formulation blends of dry ingredients by batches.
First mixing system is followed for even material blend for balance forward process.
Pulverizer grinding is the second grinding process which prepare the formulation into finner powder with 80 mesh 95% pass for example. This step can be by pass when making big extrudates with sizes of 2.5 mm and up.
Second mixing system:
Other sources like pre-mix, liquid, oil and fat are now added and mixed with raw material. Too much fat added here will affect the float ability so drum coater will be used to account for the total fat content required.
Extrusion cooking with pre-conditioning:
The mixer feeds down through a feed hopper into the feed screws which meter the ingredients into differential diameter conditioner (DDC). Water and steam are added in DDC with retention time controlled by shaft speed. Two types of extrusion technology can be chosen: single screw extruder or ContraTwin screw extruder. Both extruders have density control unit to make fast sinking and sinking extrudates. Products are cooked and shaped during extrusion cooking process.
Extrudate with 20% to 28% moisture content will be reduced to 8%~10% depend on the water activity.
Evenly distributed fat coated on the extrudates to increase the total fat contents. Depend on the fat content need to be added, drum coater or vacuum coater can be chosen.
Cooler lowers the hot pellets temperature from around 50 °C to + 2 °C of room temperature with ambient air.
Impurity and dust sieve:
All pellets will go through a vibration sieve to remove any irregular pellets or impurity before bagging.
Bagging and sealing system:
Weighing cell and bagging machines bag pellets with chosen quantity ex: 20 Kg. or 25 Kg. per bag and seal the bags for storage. Finished products can also be loaded by trucks or in container bags.
Pellet crumbling system:
Pellets conveyed into storage bins before either being packaged or being turned into crumble in the crumbling plant. Pellets can be processed by crumbler to produce smaller pellet as No.1, No.2, and No.3 products. (Sizes between 20 to 60 mesh) fines will be recycled to pellet mill section for re-use and undesired bigger pellets that pass through the sieve will be re-crumbled again.
Features and Benefits of IDAH process design and equipment
IDAH firmly believe in a strategy of design fit for purpose. We recognize the constraints our customers face with rising ingredient costs, energy costs and overheads costs, yet in the face of these challenges it is still expected that high quality products be supplied into a very competitive market. Our design philosophy is to work continuously to refine and improve process and equipment to maximize the success of our customers. The following describes some of the features and benefits resulting from this philosophy.
Rugged 24/7 Design
All our equipment is designed to be used in continuous operations, where it is expected that down time has to be minimized. It is our mission to see our equipment still working years after installation, with the only maintenance required being routine maintenance caused by normal fair wear and tear.
Formulation is important to two perspectives: culturing performances and efficiency of the machinery. For example, choose the right starch source (types of flour) is important. Flour with protein 7% ~ 12% are acceptable for floating fish feeds but sinking fish feeds required flour with protein 12% and above. Cassava is a good starch source for sinking feed. Fat and moisture content play big roles in the hammer mill and pulverizer throughput. High fiber mixes will increase wear of all machineries in the process thus reducing the life cycle of the parts especially for the hammers, screens and dies. In addition, water stability relates to fiber content level.
We offer a range of mixers, depending on customer needs and preferences. Our mixers are all of very rugged design and we continue to develop new features, such as geared shaft drives on our twin shaft mixers, which reduce noise, energy costs and maintenance costs.
Two stage Grinding and Pulverizing
We are firm believers in evenly reducing the particle size of the dry ingredients down to a very fine powder, our typical target being more than 95% passing through a 60 mesh screen. It is impossible to make products efficiently with good quality at or below 2mm in size without this fine grind, and even for larger products process efficiencies and product quality are improved when using finely ground material, not to mention that it is possible to use less expensive starch ingredients when the grind is fine. It is also extremely difficult to make small pellets from high fiber ingredient mixes unless the ingredients have been finely ground through a pulverizer. We do recognize the potential extra energy costs incurred when using a pulverizer, which is why we have created a revolutionary design that runs at much lower energy costs. The small extra energy requirement still used by the pulverizer is more than compensated for by the ability to use cheaper ingredients and downstream energy cost savings. Pellet surface will be smooth, shiny and attain good water stability when pulverized raw material is used.
We always recommend the use of pre-hydration in mixers designed to do this. The addition of even a small amount of water to dry ingredients at this early stage in the process dramatically improves throughput, energy costs and product quality. To ensure that the potentially more cohesive pre-hydrated mix can be evenly fed to the pellet mill we also supply our activated hopper system, with slowly rotating paddles in a semi-cylindrical hopper.
Our twin shaft pre-conditioners have an independent drive on each shaft, which improves power consumption and noise, and also allows the machine to be completely emptied by slowing and reversing the paddles. The addition of misting steam and water injectors further improves conditioner performance, followed by the use of steam jacketed mixer conveyors after the conditioner which creates an homogenous mix with little to no free water. Inappropriate pre-conditioning will cause cracks on pellet surface and creating more fines.
ContraTwin screw extrusion with pre-conditioning
Our ContraTwin screw extruder is breaking new ground in terms of product quality (especially when running high fibre formulations), low energy costs and low wear costs. Or machines typically make high quality aquafeeds with specific mechanical energies of 25kWh/tonne or less, and the very positive conveying action inside these machines allows us to run high fibre and small diameter products at rates others find difficult to believe.
We offer a range of dryers, both horizontal belt/conveyor dryers and vertical cross-counterflow designs. Wherever possible we prefer to offer the counterflow model to save energy costs. IDAH VC2R dryer has an especially small footprint and height compared to typical vertical counterflow dryers and also uses a lot less electrical power than most other designs, cutting down on capital costs, energy costs, maintenance costs and noise. A round shaped VCR dryer generates a very homogeneous air flow stream inside the dryer which allows an extremely uniform treatment of the product. This process air flow leads simply to the fact that over drying of the product is not given. Constant tumbling (up to seven times) of the product to be dried leads to best results in uniform water evaporation.
Batch and semi batch counterflow cooling is the most efficient way to operate, so we offer this equipment whenever possible. Note that we like to stack dryers, coaters and coolers above one another whenever possible, allowing gravity to do the work, saving yet again on energy costs, capital costs and maintenance costs.
We offer continuous drum coaters and batch vacuum coaters, depending on customer requirements. Our many years experience manufacturing coaters have given us an experience that allows us to offer efficient, rugged and reliable machines that work right first time.
Dual stage crumbling enhances the size homogeneity of the crumbled feeds and dramatically reduces the fines to increase yield rate.
Models of single screw extruders for fish feeds
Capacity ( per hour)
※Above throughput is with regular tilapia formulation with starch, fat, oil
Models of ContraTwin screw extruders for fish feeds
※Above throughput is with regular tilapia formulation with starch, fat, oil