Study of the wear processes of the working elements of crushing and screening equipment in the processing of construction waste

Abstract

Recycling of construction and demolition waste drives crushing and screening equipment into a duty for which it was not originally designed: the feed is heterogeneous in strength, contains metal inclusions and a variable share of brick rubble, and its abrasiveness is governed by the quartz aggregate of crushed concrete. The gap between the rated service life of working elements and the actual running time before replacement is attributed mainly to abrasiveness, leaving the contribution of reinforcement and of the variable feed composition unassessed. The study quantifies the wear of the working elements of a two-stage construction waste processing line and relates the loss of crushing chamber geometry to the quality of the recycled aggregate. An author's model of specific mass wear accounts for feed abrasiveness, the ratio of aggregate microhardness to the hardness of the work-hardened surface, the peripheral speed of the blow bars and the mass fraction of reinforcement; four feed compositions have been modelled for 2020-2026. The critical position proved to be the blow bars of the impact crusher, 239,7 h against 703,0 h for the jaw plates, while the growth of the discharge setting by 16,1 mm over the maintenance interval shifts product flakiness from the second group of GOST 8267-93 to the third. The marketable quality of the aggregate is lost before the working element reaches its limiting mass wear, so the limiting state of the liner should be rated by the crushing chamber geometry.