Continuous materials handling operations constitute a clear trend as well in quarry operations as in open cast mining. The decision for continuous operations is determined by many factors, such as governmental restrictions and requirements and mainly costs.  Despite that, up to today in many quarries transport by trucks was and still is standard procedure. With the steep increase of cement line throughputs up to more than 10,000 tpd and the respectively increased consumption of raw material as well as very substantial increase in fuel and tyre prices among others the operating cost have increased to a point where the conveyor transport has become economically attractive in many applications, in particular, since the distances between cement plant and quarry face are ever increasing.
Advantages of continuous extraction and transport systems other than simplicity are considerably lower costs of spares and wearing parts, lower specific power requirements, extensive independence from crude oil products, lower personnel costs, significantly lower costs for road construction and maintenance, no or low environmental pollution (dust, exhaust fumes etc.).

For the cement industry TAKRAF offers a complete package from the quarry to raw materials stockyard consisting of:
1. raw material extraction
2. raw material transport
3. raw material stocking and blending:

Raw material extraction

Depending on the material characteristics the following products can be supplied:

For Hard Rock
- fully mobile crushing plants
- semi-mobile crushing plants
- Surface miners
- associated conveyor systems

Materials with strong density and abrasiveness, blasted in the quarry mostly need to be reduced in size for conveyor transport. The application of crushers either in mobile or semi-mobile crushing stations turns out beneficial. In case of a mobile crushing station truck transport can completely be eliminated, since the crushing station permanently follows the shovel along the face. The shovel feeds the sizing rig with the blasted material. The crusher feeds the crushed material via a loading hopper onto a face conveyor from where it is transported via a connecting conveyor to a shiftable conveyor system. 

Since only one type of product is fed at a time the complete blending of the raw material has to be facilitated on the stockyard.

Semi-mobile crushing plants can be fed by trucks bringing the material from different quarry faces. Thus, the raw material quality is already controlled in the quarry. The crushing plant itself is relocated in intervals of a few years to keep truck transport distances short. Depending on the stability of the quarry face concreting work for the crusher pocket may be completely eliminated.

The surface miner is a product with a bright future in cement applications. In material with less than 100 MPa compressive strength it completely eliminates the need for blasting with its rapidly increasing cost and the reduced acceptance due to its environmental impact. Moreover, the product size of material mined with the TAKRAF – surface miner shows a very steep grain size distribution curve similar to the one out of a sizer, making the material very suitable for further processing in the cement plant.

Soft rock

For the extraction of soft material such as chalk, marl etc. the application of a TAKRAF bucket wheel excavator or TAKRAF bucket chain excavator may be considered. Both machines produce a product immediately suitable for conveyor transport.

While the bucket wheel excavator can dig harder material with less specific energy than the bucket chain excavator, the latter already blends the materials along the digging face while cutting over the full length of the face. Moreover, the bucket chain excavator often operates in deep cut. With the walking level above the cutting area it is less sensitive to precipitation and can even be operated with the bucket ladder in the water.

Raw material transport

The most economical way of raw material transport over distances ranging from some 100 metres to some kilometres is usually the conveyor transport.
Conveyor systems, such as belt or pipe conveyors override steep mountainsides, difficult curves, water barriers etc. The conveyor systems can either be stationary, shiftable or mobile. Shiftable conveyors are mounted on pontoons that can be tugged sidewards by crawlers for a half meter when the system is out of gear.

Depending on the terrain TAKRAF offers throughed belt conveyor or pipe conveyor systems. For wear and maintenance reasons customers tend more and more to use single flight curved conveyor systems rather than connecting a number of straight conveyors by transfer towers. The longest single flight belt conveyor TAKRAF has built so far has a length of 16.7 kilometres. It has been successfully operating for many years now in the USA at temperatures ranging from +30°C to – 30°C.

For tight curves and steep slopes a pipe conveyor system can be the best solution.
Crawler mounted conveyor systems do provide the necessary flexibility to follow mobile or semi-mobile machines in quarries.

Raw material stacking and blending

Be it facilities for materials blending and homogenization, like stackers and reclaimers, transfer towers, thawing stations or stations for sample taking, TAKRAF provides its customers with complete systems. TAKRAF’s vast capability in raw materials’ extraction and raw materials’ storage from limestone to gypsum and coal enables us to find the best operation solutions for quarries too.

TAKRAF offers a wide range of stockyard machines for stacking and blending raw material in cement plants, among others:

Slewable/ non-slewable stackers
Scraper reclaimers of various types and capacities
Conveyor systems.

The references cover the full area of raw materials, such as lime stone, gypsum, coal, iron ore etc.

In the course of technological development TAKRAF succeeded gathering expertise of different sub-areas to effectively access and utilize the decades-long accumulated know-how for its customers. The support by the Techint Group, the owner of TAKRAF with its vast expertise in materials handling but also as an EPC- and service contractor will allow TAKRAF to offer an even more comprehensive package to its customers in the cement industry.