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EP-4520434-B1 - METHOD OF PROCESSING CONCRETE DEMOLITION MATERIAL INTO A PLURALITY OF PARTICLE SIZE FRACTIONS

EP4520434B1EP 4520434 B1EP4520434 B1EP 4520434B1EP-4520434-B1

Inventors

  • Javelle, Olivier
  • Fittere, Michel
  • Guillin, Anthony
  • Marbec, Olivier

Dates

Publication Date
20260513
Application Date
20230908

Claims (11)

  1. A method of processing concrete demolition material (2) into a plurality of particle size fractions, comprising: - providing particles of concrete demolition material (2), - crushing the particles by means of a high-pressure grinding roll (1) comprising a pair of counter-rotating rolls mounted in a frame, wherein one roll is a fixed roll (3) fixed in a frame and the other roll is a floating roll (4) positioned at a variable distance from the fixed roll (3) by means of a hydraulic cylinder system (7), thereby obtaining a crushed material (10), - screening the crushed material (10) in order to obtain at least two, in particular at least three, particle size fractions (12,13,14); and characterized in that the hydraulic cylinder system limits the maximum pressure exerted on the particles.
  2. Method according to claim 1, wherein the particles are subjected to a maximum pressure of 0.3 to 1 N/mm 2 .
  3. Method according to claim 1 or 2, wherein a precharge pressure of the hydraulic cylinder system (7) is set at 50-70 bar.
  4. Method according to claim 1, 2 or 3, wherein a gap between the fixed roll (3) and the floating roll (4) in the relaxed position of the hydraulic cylinder system (7) is set to 8-12 mm, preferably 10 mm.
  5. Method according to any one of claims 1 to 4, wherein the rotation speed of the rolls (3,4) is set to 80-160 rpm, preferably 100-140 rpm.
  6. Method according to any one of claims 1 to 5, wherein the particle size fractions comprise a fine fraction (14) having a particle size in the range of 0-4 mm, a medium fraction (13) having a particle size in the range of 4-10 mm and a coarse fraction (12) having a particle size in the range of 10-30 mm.
  7. Method according to claim 6, wherein the fine fraction (14) comprises an ultra-fine fraction (17) having a particle size in the range of 0-500 µm and a standard fine fraction (16) having a particle size in the range of 500µm-4mm.
  8. Method according to claim 7, wherein the method further comprises using the ultra-fine fraction (17) as supplementary cementitious material in a composite cement, preferably after having been subjected to a re-carbonation step of contacting the ultra-fine fraction with a CO 2 containing gas.
  9. Method according to claim 6, 7 or 8, wherein the method further comprises using the standard fine fraction (16) as a partial substitute to sand in a concrete or mortar composition.
  10. Method according to any one claims 6 to 9, wherein the method further comprises using the medium fraction (13) and the coarse fraction (12) as aggregates in a concrete composition.
  11. Method according to any one of claims 1 to 10, wherein the particles of concrete demolition material (2) have a size in the range of 8 to 30 mm.

Description

The invention refers to a method of processing concrete demolition material into a plurality of particle size fractions. The cement industry is an important emitter of CO2. Within the cement production process, significant amounts of CO2 are generated during the decarbonation of raw meal (containing CaCO3) to lime (CaO). During the production of Portland cement clinker about 0.7 tons of CO2 per ton of Portland cement clinker are emitted by the calcination of the raw materials and from the fuel combustion in the rotary kiln. By substituting supplementary cementitious materials for Portland cement the specific emission of CO2 in the production of cement can be reduced. Supplementary cementitious materials comprise a broad class of siliceous or siliceous and aluminous materials which, in finely divided form and in the presence of water, chemically react with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties. Examples of supplementary cementitious materials include granulated blast-furnace slag, fly ash, natural pozzolans, burnt oil shale, or calcined clay. There have also been attempts to recycle concrete demolition materials so as to make them useable as a component of composite cements. The prior art in the field of construction and demolition materials management has predominantly focused on disposal methods, with a limited scope for high-value utilization. The generation of construction and demolition materials, particularly concrete, is extensive, leading to considerable environmental and logistical challenges. Traditional disposal methods, such as landfilling, are not only environmentally damaging but also economically inefficient due to the rising costs associated with landfill space. Furthermore, the current industry practice of using concrete demolition materials for low-value applications, such as road sub-base material, does not fully exploit the potential of this resource. There has been a growing interest in the reuse of concrete demolition materials as a supplementary cementitious material to partially replace cement in new cement and concrete production. Prior art methods of separating concrete demolition material into multiple particle size fractions have involved various mechanical processes, including traditional crushers, ball mills, and hammer mills. While these systems can effectively segregate particles to some extent, they often suffer from various shortcomings. One major drawback of conventional systems is their inability to differentiate between different components of the concrete. This means that valuable components, such as gravel, often undergo undue crushing, reducing their usability for certain applications where larger particle sizes are desired. This not only results in the loss of potential valuable aggregate but also increases the energy consumption due to unnecessary processing. Furthermore, conventional methods often produce inconsistent particle sizes, resulting in fractions that may not meet the required standards for use as replacement materials. The uneven size distribution often necessitates further processing steps, increasing costs and resource consumption. Conventional methods of processing concrete demolition material are shown in documents CN110252458B, CN113769819A and CN219377259U. Therefore, the present invention aims at providing a more efficient and precise approach to process concrete demolition material particles into a plurality of particle size fractions. In particular, the object is to enhance the reusability of demolition waste, thereby contributing to more sustainable construction practices. To achieve these and other objects, the invention provides a method of processing concrete demolition material into a plurality of particle size fractions, comprising: providing particles of concrete demolition material,crushing the particles by means of a high-pressure grinding roll comprising a pair of counter-rotating rolls mounted in a frame, wherein one roll is a fixed roll fixed in a frame and the other roll is a floating or mobile roll positioned at a variable distance from the fixed roll by means of a hydraulic cylinder system, thereby obtaining a crushed material,screening the crushed material in order to obtain at least two, in particular at least three, particle size fractions, wherein the hydraulic cylinder system limits the maximum pressure exerted on the particles. The invention provides a method for processing concrete demolition material into distinct particle size fractions using a high-pressure grinding roll configured with a fixed and a floating roll. This setup is specifically designed to ensure pure attrition grinding, which distinguishes it from conventional crushing mechanisms. Utilizing a high-pressure grinding roll for the processing offers the advantage of a consistent and controlled grinding process. The pure attrition grinding ensures that the particle size reduction is achieved through surfac