Patent ID: 6796432
Filing Date: 2004-09-28
Classification: B01F,B03B,G05D

Abstract:
A method of reblending aggregate comprising:delivering aggregate of various sizes to a classification tank for reblending, the classification tank having an inlet and a plurality of stations Si arranged at progressively greater distances from the inlet for collecting the aggregate through settling, where i equals 1 through the number of stations N in the plurality of stations, S1 being closest to the inlet and SN being farthest from the inlet, each station having a plurality of discharge valves therein, the plurality of discharge valves including a primary discharge valve and a secondary discharge valve; calibrating the tank to determine raw feed analysis; defining valve discharge rates in terms of total valve open time at each station over the total valve open times at all of the stations; inputting into a computer for controlling the tank a specification for a desired primary product including a quantity of the desired primary product and a desired distribution of various aggregate sizes in the desired primary product including fine aggregate; operating the tank in a production mode and collectively controlling the discharge valves on a percentage basis at a given station which for the primary discharge valve setting is defined as a ratio of the primary discharge valve open time over the total valve open time for a given station and which for the secondary discharge valve is defined as a ratio of the secondary discharge valve open time over the total valve open time for a given station; then adjusting the valve discharge rate at one or more stations and valve percent setting for one or more valves at each station to divert material away from the primary discharge valve as necessary to bring a primary projected final product into conformance with the specification for the desired primary product; wherein the adjusting step includes setting i=N and the substeps of: a) computing the primary projected final product being discharged from the tank; b) comparing the primary projected final product to the specification for the desired primary product; c) when the primary projected final product exceeds the specification for fine aggregate, selecting the open station located farthest from the inlet of the classification tank and adjusting the primary discharge valve by reducing the percentage of primary valve open time by a given amount; d) then repeating steps a-c as necessary until the primary projected final product is in specification or the primary discharge valve of station Si is completely closed; e) when the primary valve of station Si is completely closed and the primary projected final product is still out of specification, then decrease i by one and repeat steps a-d until the primary projected final product is in specification or the primary discharge valve at each station has been completely closed.