Translation of "Raw mill" in German

For the production of cement clinker, raw materials 1 are ground in a raw mill 2 .

All raw materials are ground together in a raw mill and at the same time dried.

Hydrated lime can be charged into the raw mill together with the raw material constituents or directly added to the kiln feed.

In cement kiln systems, this temperature range is usually reached in the area between the raw mill and the dust collector

In the context of the production of cement, in addition, sulphur can be incorporated in the raw material in the raw mill.

Throttling means 17 and 18 serve solely for setting the kiln waste gas quantity supplied to the raw meal mill or directly to the electrofilter 5.

The remaining proportion of the waste gases (possibly after previous utilization of the heat content in the raw meal mill not illustrated) is dedusted in the electrofilter 5.

Thus, the kiln waste gas conveyed by the kiln waste gas fan is divided into a volume flow supplied to the raw meal mill (and the following electrofilter) and a volume flow conducted to the bypass system.

Should these prove insufficient, then there is the possibility of introducing a residual part-stream of the exhaust gases from the raw meal preheater 2 into the raw-grinding mill 4a as additional drying gases.

The mixing zone is preferably formed by a mixing silo or mixing vessel 19 which can be constructed in a known manner and in which the receiving capacity is adapted according to the operating conditions to approximately the grinding capacity (t/h) of the raw mill 9 occurring once to three times an hour.

In each case, however, the total raw material mass flow from the raw mill 9 is conveyed directly into the mixing vessel 19.

Moreover, in the case of a--desired or undesired--shutdown of the raw mill 9, from the storage silo 20 the raw meal mixture can be conveyed directly to the burning arrangement 10 or by way of the mixing vessel 19 to the burning arrangement 10 or also, in adjustable quantities, some can be conveyed directly to the burning arrangement 10 and some by way of the mixing vessel 19 to the burning arrangement 10.

In the first filling of the storage silo 20 or after a kiln shutdown without stock remaining it may further be advantageous to convey the entire mass flow from the raw mill 9 either by way of the mixing vessel 19 or directly--by way of the corresponding bucket elevator--into the storage silo 20 in order to be able to fill up the latter particularly quickly.

In direct operation of the apparatus (raw mill stationary) the raw meal mixtures produced at different times cannot be blended again, since the total quantity of the raw meal mixture required by the burning arrangement 10 is then only conveyed directly from the storage silo 20.

If in this third embodiment direct operation must be employed (raw mill stationary), then the raw meal mixture is delivered from the storage silo 20 only by way of the mill bucket elevator 29 and the mixing vessel 19 as well as the kiln bucket elevator 30 to the burning arrangement 10.

With the aid of the proportioning belt scales 5 to 8 the individual raw material components can be proportioned according to their chemical compositions in predetermined proportions by weight or by quantity and can be jointly fed as a raw material combination to the raw mill 9, which can preferably be a roll grinding mill but, if appropriate, also a roller mill.

For this purpose material samples are removed from the comminuted material periodically at specific time intervals with the aid of an automatic material sampling station, for example at the outlet of a raw mill.

In this raw mill 9 the raw material components which can be delivered in adjustable quantities are jointly comminuted or ground to a predetermined fineness.

The aforementioned apparatus parts lie in the flow path of the kiln waste gases, and the latter can be supplied either via a waste gas conduit 20 firstly to a raw meal mill (not illustrated in the drawing) or directly to the electrofilter 5.