A crushing unit, comprising a first belt conveyor and a second belt conveyor having a conveying upper run presenting a feed end, a discharge end and a return lower run, wherein the conveying upper run comprises a curved extension, which is concave and ascending and which presents an inlet lower portion and an outlet upper portion, the latter ending at the discharge end of the conveying upper run, the first belt conveyor conducting bulk material to a classifying screen whose discharge of rejected large material feeds a crusher, which releases the crushed material to a feed end of the conveying upper run of the second belt conveyor, the discharge end of the curved extension being lifted for discharging the crushed material to the feed end of the first belt conveyor; and the feed end of the first belt conveyor being positioned in a curved extension of the second belt conveyor, the first belt conveyor being vertically disposed above the second belt conveyor, characterized in that the material support face of the curved extension presents opposite marginal portions, each seated on a corresponding support roller whose radius of curvature defines the radius of curvature of the curved extension; the second belt conveyor imparts to the material a path that is substantially coplanar and opposite in relation to that imparted to the material in the inlet lower portion, said ascending curved path presenting a curvature so as to produce, on the material conveyed at a determined belt speed, a centrifugal force sufficient to maintain said material seated against the curved extension of the conveying upper run, until reaching the discharge end, the feed end of the first belt conveyor is mounted around a roll provided internally and coaxially in relation-to said support rollers, and the second conveyor belt further comprises a linear extension arranged immediately downstream of the feed end and ending in the inlet portion of the curved extension. the first belt conveyor conducting bulk material to a classifying screen whose discharge of rejected large material feeds a crusher, which releases the crushed material to a feed end of the conveying upper run of the second belt conveyor, the discharge end of the curved extension being lifted for discharging the crushed material to the feed end of the first belt conveyor; and the feed end of the first belt conveyor being positioned in a curved extension of the second belt conveyor, the first belt conveyor being vertically disposed above the second belt conveyor, the material support face of the curved extension presents opposite marginal portions, each seated on a corresponding support roller whose radius of curvature defines the radius of curvature of the curved extension; the second belt conveyor imparts to the material a path that is substantially coplanar and opposite in relation to that imparted to the material in the inlet lower portion, said ascending curved path presenting a curvature so as to produce, on the material conveyed at a determined belt speed, a centrifugal force sufficient to maintain said material seated against the curved extension of the conveying upper run, until reaching the discharge end, the feed end of the first belt conveyor is mounted around a roll provided internally and coaxially in relation-to said support rollers, and the second conveyor belt further comprises a linear extension arranged immediately downstream of the feed end and ending in the inlet portion of the curved extension.