Methods for the retrieval of aggregate from waste construction material by grinding
Methods for the retrieval of aggregates from waste construction material by grinding in a ball mill or on a compressive grinder, which are useful in the recycling of waste construction material, especially in the recycling of concrete or mortar. Also, cleaned aggregates obtained from waste construction material by grinding and their use on the production of new construction materials.
1 . A method for retrieval of aggregates from waste construction material, the method comprising a step of grinding the waste construction material, wherein:
the waste construction material comprises at least one aggregate and at least one mineral, hydraulic binder;
the grinding is done in a ball mill or in an agitation mill; and
a mass ratio of waste construction material to grinding media is 0.2:1 to 3:1.
2 . A method as claimed in claim 1 , wherein a filling degree of the mill is not higher than 60%, based on a volume of the mill.
3 . A method as claimed in claim 1 , wherein the grinding media is selected from balls, rods, pebbles, or pieces of steel, zirconium oxide, aluminum oxide, ceramics, natural stone, concrete, or mortar.
4 . A method as claimed in claim 1 , wherein the grinding media has a minimum size which is larger than a maximum particle size of the aggregate to be retrieved.
5 . A method as claimed in claim 1 , wherein a grinding aid is added before and/or during the grinding of the waste construction material.
6 . A method according to claim 5 , wherein the grinding aid is selected from the group consisting of polycarboxylate ethers, alkanolamines, sugars, sugar acids, hydrogenated sugars, super absorbent polymers, glycols, glycerine, calcium formiate, and mixtures thereof.
7 . A method as claimed in claim 5 , wherein the grinding aid is added in an amount of 0.01-10 w %, relative to a total dry weight of the waste construction material.
8 . A method as claimed in claim 1 , wherein the method additionally comprises a step of carbonation of the waste construction material.
9 . A method as claimed in claim 8 , wherein the carbonation of the waste construction material is effected during the grinding of the waste construction material.