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CN-122010440-A - Construction waste recycling separation process

CN122010440ACN 122010440 ACN122010440 ACN 122010440ACN-122010440-A

Abstract

The invention provides a construction waste recycling separation process, which belongs to the technical field of solid waste recycling, and comprises the following steps of S1, crushing and screening construction mixed waste, separating and preparing recycled fine aggregate, recycled concrete powder and recycled brick powder, S2, placing the recycled fine aggregate in a fluidized bed reactor, introducing carbon dioxide-containing gas for pre-carbonization treatment to obtain pre-carbonized recycled fine aggregate, S3, providing slag powder, mixing the recycled concrete powder, the recycled brick powder and the slag powder according to a preset proportion, mechanically grinding to obtain gelled powder, S4, uniformly mixing the pre-carbonized recycled fine aggregate, the gelled powder, water and an additive to obtain a mixture, and compacting the mixture to obtain a blank, and S5, placing the blank in a closed container for curing under a carbon dioxide atmosphere to obtain full-solid waste concrete. The process of the invention improves the mechanical properties of the solid waste concrete material.

Inventors

  • LI SONG
  • CHEN XIN
  • JIAO BING

Assignees

  • 徐州源盛环保材料有限公司

Dates

Publication Date
20260512
Application Date
20251224

Claims (10)

  1. 1. The construction waste recycling separation process is characterized by comprising the following steps of: Step S1, crushing and screening the building mixed garbage, separating and preparing recycled fine aggregate, recycled concrete powder and recycled brick powder; s2, placing the recycled fine aggregate in a fluidized bed reactor, and introducing gas containing carbon dioxide to perform pre-carbonization treatment to obtain pre-carbonized recycled fine aggregate; Step S3, providing slag powder, mixing the recycled concrete powder, the recycled brick powder and the slag powder according to a preset proportion, and mechanically grinding to obtain gelled powder; Step S4, uniformly mixing the pre-carbonized regenerated fine aggregate, the gel powder, water and the additive to obtain a mixture, and pressing the mixture to form a blank; And S5, placing the blank body in a closed container, and curing under the carbon dioxide atmosphere to obtain the full-solid waste concrete.
  2. 2. The process according to claim 1, wherein in step S1, the crushing and screening steps comprise, in particular, impact crushing of the construction mixed waste using a reaction crusher, controlling the rotor linear speed of the crusher to be 25m/S to 30m/S, and screening the crushed material by a screen with a pore size of 10mm, separating the material into oversize and undersize.
  3. 3. The process according to claim 2, wherein the steps of separating and preparing the recycled fine aggregate, recycled concrete powder and recycled brick powder specifically comprise collecting the oversize material and performing impact shaping and classification, selecting particles with a particle size of 0.15mm to 2.0mm as the recycled fine aggregate, selecting powder with a particle size of less than 0.15mm as the recycled concrete powder, and returning the particles with a particle size of more than 2.0mm to impact shaping equipment for crushing again, collecting the undersize material and performing grinding and powder selection, and selecting powder with a particle size of less than 0.15mm as the recycled brick powder.
  4. 4. The process according to claim 1, wherein in step S2 the carbon dioxide-containing gas has a carbon dioxide volume concentration of 20% to 30%, and the gas has a flow rate in the fluidized bed reactor of 1.5 to 2.0 times the critical fluidization velocity of the recycled fine aggregate.
  5. 5. The process according to claim 4, wherein the pre-carbonization treatment is carried out at a temperature of 25 ℃ to 35 ℃, a relative humidity of 55% to 65% and a treatment time of 10 minutes to 20 minutes.
  6. 6. The process according to claim 1, wherein in the step S3, the mass percentages of the components in the gelled powder are 30-40% of recycled concrete powder, 30-40% of recycled brick powder and 20-30% of slag powder, and the sum of the mass percentages of the components is 100%, and the particle sizes of the recycled concrete powder and the recycled brick powder are less than 0.15mm.
  7. 7. The process according to claim 1, wherein in step S3, the mechanical grinding is performed by a planetary ball mill with a ball-to-material ratio of 10:1, a rotation speed of 400rpm and a grinding time of 30 to 60 minutes.
  8. 8. The process according to claim 1, wherein in step S4, the additive comprises an alkali-activator and a polycarboxylate water reducer, the alkali-activator is water glass with a modulus of 1.2 to 1.5, the mixing amount of the alkali-activator is 3 to 5% of the mass of the gelled powder, the mixing amount of the polycarboxylate water reducer is 0.5 to 2.0% of the mass of the gelled powder, the mass ratio of pre-carbonized regenerated fine aggregate to gelled powder in the mixture is 1.0:1 to 1.5:1, and the mass ratio of water to gelled powder in the mixture is 0.16:1 to 0.20:1.
  9. 9. The process according to claim 1, characterized in that in step S4, the pressure of the press forming is 15MPa to 20MPa.
  10. 10. The process according to claim 1, wherein in step S5, the specific process conditions of the curing are that the pressure of the carbon dioxide gas is 0.2MPa to 0.5MPa, the purity of the carbon dioxide gas is 95% or more, the curing time is 24 hours to 48 hours, and the relative humidity is less than 60%.

Description

Construction waste recycling separation process Technical Field The invention belongs to the technical field of solid waste recycling, and particularly relates to a construction waste recycling separation process. Background The recycling technology of construction waste, especially converting the construction waste into recycled concrete aggregate, is widely regarded as a key way for realizing green cyclic development of the construction industry because of the great potential of the construction waste in the aspects of recycling solid waste and reducing carbon emission in the construction industry. However, the conventional recycled aggregate is extremely susceptible to the deterioration of performance due to the microstructure of hardened cement mortar (i.e., old mortar) attached to the surface thereof during the preparation and service of concrete. For example, the loose and porous characteristics of the old mortar lead to the water absorption of aggregate being obviously higher than that of natural stone, the water in the slurry can be adsorbed vigorously at the initial stage of concrete mixing, so that the working performance is suddenly reduced, and meanwhile, the lower strength of the old mortar and microcracks existing in the old mortar enable the old mortar to be weak links in the stress transmission process, so that the bearing capacity and the service life of the recycled concrete are obviously reduced. To obtain usable recycled aggregate, simple mechanical crushing and screening processes are currently commonly employed in the industry in an attempt to dissociate the waste concrete from the bricks by physical comminution. However, the conventional physical processing technology has obvious inherent defects that the conventional crushing is difficult to realize high-purity separation of components due to obvious differences in hardness and crushing characteristics of concrete and clay bricks, and an old mortar layer tightly combined with the surface of aggregate cannot be thoroughly stripped. In the hardening process of recycled concrete, the heterogeneous structure is extremely easy to cause complex interface transition region defects, namely multiple and through pore networks are formed among new slurry, old mortar and original aggregate, so that the material has poor impermeability and cannot provide long-term and stable mechanical properties. In the prior art, a large amount of regenerated micro powder (smaller than 0.15 mm) with extremely fine particle size is inevitably generated in the process of crushing and shaping the construction waste. However, the micro powder is treated by direct landfill or treatment as low-activity filler. The regenerated micro powder mainly comprises hydrated cement products and finely divided brick powder, the surface of the regenerated micro powder is chemically inert, and the particle morphology is extremely irregular. In conventional cement-based systems, these fine powders are not only difficult to exert gelling activity, but rather increase water demand due to large specific surface area, which is extremely liable to cause shrinkage cracking of the slurry. The method not only causes great waste of potential gelling resources, but also forces the production of recycled concrete to still rely on a large amount of high-carbon emission portland cement to make up for the deficiency of strength, and the low-carbon manufacturing of materials cannot be truly realized. Disclosure of Invention In view of the foregoing, it is an object of the present invention to provide a recycling and separating process for construction waste, which at least partially solves the problems set forth in the background art. The technical scheme adopted by the invention is as follows: the invention provides a construction waste recycling separation process, which comprises the following steps: Step S1, crushing and screening the building mixed garbage, separating and preparing recycled fine aggregate, recycled concrete powder and recycled brick powder; s2, placing the recycled fine aggregate in a fluidized bed reactor, and introducing gas containing carbon dioxide to perform pre-carbonization treatment to obtain pre-carbonized recycled fine aggregate; Step S3, providing slag powder, mixing the recycled concrete powder, the recycled brick powder and the slag powder according to a preset proportion, and mechanically grinding to obtain gelled powder; Step S4, uniformly mixing the pre-carbonized regenerated fine aggregate, the gel powder, water and the additive to obtain a mixture, and pressing the mixture to form a blank; And S5, placing the blank body in a closed container, and curing under the carbon dioxide atmosphere to obtain the full-solid waste concrete. In some embodiments of the invention, in the step S1, the crushing and screening step specifically comprises the steps of carrying out impact crushing on the construction mixed garbage by using a reaction crusher, controlling the li