Skip to main content
European Commission logo print header
Contenido archivado el 2022-12-27

COMBINED USE OF ROLLING AND MILLING TECHNIQUES ON THE RAW MIX FOR A CEMENT FACTORY

Objetivo

The aim of this project is to demonstrate that an economic energy saving of about 1500 TPY can be achieved in a cement factory, by suitably modifying the utilization of the existing press and mill devices.
After starting up the facility and checking that the raw mix quality was maintained with the pre-pressing process, measurements were made of production and electrical consumption, using the graphs obtained from the central control computers on dates close to those of the outline enclosed. The following results were obtained :L% - Average raw mix production = 120 MT/hr.L% - Maximum raw mix production = 140 MT/hr.L% - Specific electrical energy consumption per tonne of raw mix milled without pressing = 20,44 kWh/MT.L% - Specific electrical energy consumption per tonne of raw mix milled with pressing = 16,44 kWh/MT.L% - Energy saved by working with press = 4 kWh/MT.L% In view of these results, and in order to increase production, the firm HUMBOLDT, which had supplied the press, carried out "in situ" tests between November 13th and 18th 1989. They concluded that production capacity and energy saving could not be improved, due to lack of product recirculation from mill to press, because the pressinstallation was originally designed to work only with clinker and additions to make cement. Its location with regard to the raw mix milling installation makes recirculation practically unfeasable. If recirculation had been possible, the increase in production would have been approximately 15%.L% They therefore proposed the following:L% - Modifying the existing raw mix separator in order to differentiate the "finer" coarse material, which would be returned to the mill, and the coarse material, which would be sent, in part, to the press feed hopper. Thus, the pressing process could be optimized and a further 25 MT/hr approximately of finished material could be processed.L% - Optimizing the gas circulation conditions in the milling plant (uprating the fan and increasing pipe diameter)L% In view of the difficulty of carrying out these modifications due to the long distances over which the material to be recirculated would have to be recirculated would have to be carried, KHD's proposal was not possible.L% ECONOMIC RESULTSL% The real cost of the facility totalled 257.104.221 ptas, broken down as follows:L% - Personnel cost 7.054.297 Ptas.L% - Materials, apparatus and equipment wholly devotedL% to the project 238.290.662 Ptas.L% - Outside assessment, studies and services 11 759.262 Ptas.L% TOTAL 257.104.221 Ptas.L% The annual saving was calculated on the basis of the following hourly rates:L
% Working days Sat./Sun./HolidaysL% Peak time 16.20 ptas/kWh ---L% Regulat time 8.10 L% L% ---Off peak time 4,62 4,62 kWh In 1989 and the first months of 1990 the saturation workload of the press in cement milling meant that the annual savings was less than expected.
Commonly, production of raw mix and cement in cement plants is carried out through direct process of material in ball mills or vertical roller mills, with no intermediate process. Currently, roller presses are being introduced in to the process, with very satisfactory results (output increase and energy saving), previously to cement ginding in order to break material crystallography and increase its grindability.
Based on the success achiered in cement lines and through experiences and tests at laboratory level, a plant is proposed to be installed using the existing HUMBOLDT RP 115/100 roller press for pregrinding cement and raw mix, joining two totally separated production lines in one point. The result of this modification was the saving of energy in the process, reducing the specific consumption of electric power per tonne of ground raw mix, better use of lower energy cost and 100% increase of current hourly production of ground raw mix.
Since the needs of the cement mill do not saturate the roller press, it is possible to take advantage of the remaining hours to press raw mix before it is sent to the raw mix mill, which would, given these conditions, increase its output while lowering its overall specific consumption.
Raw mix mill : 0 3,8 x 7,5 m
Power motor installed : 1600 kW.
Roller press : RP HW 115/100
Power motors : 2 x 300 kW.
Basically, the following pieces of equipment were incorporated into the installation:
- Two dosing scales for up to 300 MT/hr. at the exit from the press raw material feed hoppers. - Conveyor belts for up to 250 MT/hr for transporting raw materials to the press.
- Extension of the existing pressed clinker elevator in order to gain height and discharge raw mix from the press onto the conveyor belts which carry it to intermediate storage.
- Two dosing scales for up to 200 MT/hr at the exit from the intermediate storage hoppers for dosing the feed to the mill.
- Conveyor belts for up to 250 MT/hr for transporting the pressedraw mix from intermediate storage to the raw mix mill feed.
- Modification of two elevators from 110 MT/hr to MT/hr to send the milled raw mix to the homogeneization silos.
- Auxiliary equipment for the proper working of the facility, such as dust filters, metal detector and separator, cannon hoppers for pressed product, compressed air networks, etc.
- Auxiliary eqiupment for circuit link-up so that the raw mix mill can work without pressed material (emergency circuit).

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

CEMENTOS LEMONA SA
Aportación de la UE
Sin datos
Dirección
ALAMEDA DE URQUIJO, 10
48008 Bilbao
España

Ver en el mapa

Coste total
Sin datos