Efficient primary screening even under difficult conditions

Efficient Primary Screening Of Gravel Even Under Difficult Conditions

The challenge

The lowlands of northern Germany generally have a high proportion of fine sand, which imposes special requirements on sand and gravel processing. In order to economically process the relatively low proportions of gravel present, effective primary screening is required.
This was precisely the challenge faced by one of Germany’s largest gravel producers, which manufactures a high-quality range of concrete aggregates. A concept was sought to reduce the sand content in the feed material upstream of the main processing plant. The objective is to reduce energy and water requirements and cut operating costs. At the same time, environmental protection is given top priority.

HAVER & BOECKER NIAGARA as an experienced partner in the development of innovative solutions in the field of processing technology

HAVER & BOECKER NIAGARA is an experienced partner in the development of innovative solutions in the field of processing technology. The company develops successful concepts in this field for domestic and foreign markets and enjoys strong references that it can provide to potential clients.

The innovative solution: You have to try the impossible to achieve the possible

For the current project, HAVER & BOECKER NIAGARA developed a complete solution for the specified task and was able to convince with an efficient primary screening of gravel. The concept provides for pre-screening at a separation cut of approx. 2-3 mm. The maximum feed rate of earth-moist material onto the screening plant is approx. 350 t/h, while enormous amounts of energy and water are saved. The pre-screening system consists of two NIAGARA double-deck screening machines arranged in tandem one behind the other. The successful use of Niagara T-Class 1800×4000 increased the output of the existing processing plant by more than 100% and processed the maximum possible proportion of usable gravel.

The upper decks serve as protection and relief decks. On the lower decks, the actual pre-screening takes place at a separation cut of approx. 2-3 mm. A special harp screen with an extremely long mesh is used as the screen bottom. In addition, the wire screen media is excited by rubber tapping balls. The screening machines are designed in such a way that a certain amount of coarse grain with a corresponding drop height is added to the lower deck for further excitation of the screen bottom.
The inclination of the screen decks, amplitude, shore hardness and diameter of the tapping balls from the preliminary project were consistently taken into account to ensure compliance with the screen specifications. In addition to the dynamics of the NIAGARA screening machines, these are all long known requirements whose exact consideration ensures the separation success.

Sensible combination of measures for efficient pre-screening of gravel

Due to the sensible combination of measures, the screening plant can be operated without clogging even with moist material in all weather conditions. In order to allow a quick and maintenance-friendly change of the longitudinally tensioned screen media in the lower deck of the screening machines, hydraulic quick-action clamping systems are used, which allow an effortless mounting and tensioning of the screen mesh. Thus, the preliminary sand screening relieves the downstream gravel washing plant. This leads to a reduction of the washing water consumption respectively to an increase of the plant capacity.

In addition to the screening machines, the scope of supply of the HAVER & BOECKER NIAGARA consisted of steel construction, chute system, skip conveyor, installation, commissioning and planning of the entire plant.

You have to try the impossible to achieve the possible. Thanks to the good cooperation between the plant operator and HAVER & BOECKER NIAGARA, the plant was commissioned in a very short time and now makes an important contribution to efficient and resource-saving gravel processing. Efficient pre-screening thus proved to be possible even under difficult conditions, if only you put your trust in the right partners.