The flow rate of bulk solids can be determined by dosing processes. Also the total amount of the product is measured. For the dosing it is essential that enough product is available.

Continous dosing of free flowing products

Fig.4: Installation of Flow Controller FC3 with the advantage of low height

The dosing of easily flowing bulk solids is commonly realised as volumetric dosing. Because of varying product attributes it is often inaccurate, especially in case of granulates, pellets or grain goods. Gravimetric measurement has the advantage to eliminate these attributes.

Dosage usually takes place at an outlet of a silo or container. In many cases there is not many space inbetween outlet port and conveyor (chain conveyor, elevator, e.g.). The overall height sometimes allows less than 30 cm of space. Because of this problem, we constructed a feed gate, which has a height of 135 mm if the outlet is quadratic or a hight of 220 mm if the outlet is round.

Bag filling of free flowing products

Despite the fact that bulk loading becomes increasingly important, bag filling is still a major packaging solution in most bulk processing industries. The speed and reliability of this solution is of high importance.
FRIEDRICH electronic provides a low-cost alternative for bag filling with accuracy of <1%. In this case the batch amount is entered at the device and initiated manually. Alternatively a remote preselection can be implemented. This type of bag filling is not fully automated since the user must fit the bags manually.

Big bag filling and emptying for free flowing products

A frequently used batch size for packing of bulk solids are big bags. They offer an intermediate size which is easy to handle and which may contain a considerable amount of bulk. The fast and reliable filling and emptying of big bags represents a challenge to the bulk technologies.
FRIEDRICH electronic offers an easy solution for filling or emptying of big bags at measuring tolerances <1%. The batch size may be chosen deliberately and can be triggered either manually or remotely.

Continuous dosing of heavy flowing products

Fig.3: control circuit of cohesive bulk solids  Besides registration of quantities the dosage plays an important role in processing of bulk solids. Usually the dosing is performed by a volumetric controlled screw. Therefore it is necessary to assume a constant density of product. Effectively most products do not have constant density. To achieve an exact dosage a scale is necessary.

We realise gravimetric dosing of heavily flowing products by

  1.  measuring the weight of bulk-flow with the Rotor Weigher and
  2. derously driving a screw or volumetric conveyor (depending on attributes of product and constructional conditions).

Regulation (including input of target capacity) and evaluation is performed by an electronic, easily to handle. An intergrated controller adjusts a frequency converter (FU) which drives the rotation speed to the target flow. The result is an exact continuous dosage of heavily flowing products.


By Realization of such a dosing system it is possible to produce blendings continuously. Thereby it is possible to continuously weigh, dose and blend heavily flowing products in one process step. By input of percentaged proportions, individual material flow lines can be determined accurately. Using the weighing signals, the evaluation electronic regulates the t/h flow rate, which is conveyed by the screws. Subsequently these material flows are being merged. The proportion ratio is already accomplished.
An advantage of this method is the immediate homogenization: Compared to batch mixers, which are filled consecutively and – initially – inhomogeneously, these lines are merged online. This largely reduced energy costs. Also a combination of this method with batch mixers is possible and can help to reduce the mixing costs.