Method of producing metal flake

Claim 1

A continuous method of making metal flake in a ball mill comprising the steps of: (a) feeding a charge of metal particles substantially continuously to a vibratory mill containing milling material; (b) supplying a controlled amount of lubricant to the mill to avoid formation of agglomerations in amounts which would hinder metal particle flow; (c) feeding a supply of gas to the mill, the gas feeding being controlled to a rate which avoids substantial interference with metal particle flow through the mill; (d) milling the metal particles in the presence of the gas to form metal flake, the milling being controlled so as to substantially eliminate welding of the metal particles; (e) moving the particles through the mill by use of the vibratory milling action; and (f) removing metal flake and gas from the mill at a rate substantially commensurate with feed rate.

Claim 23

A method of making aluminum flake in a ball mill comprising the steps of: (a) providing aluminum particles in a mix containing 0.75 to 1.5 wt.% stearic acid; (b) feeding the mix substantially continuously to a vibratory ball mill; (c) supplying a gas containing nitrogen and 8 to 10 vol.% oxygen to the mill, the gas being supplied at a rate not greater than 7 ft 3 /min and having a flow direction in the direction of metal flow; (d) milling the aluminum particles in said vibratory mill for a residency period in the range of 0.5 to 20 hours to form aluminum flake having a surface area in the range of 3.5 to 20 m 2 /gm and moving the particles through the mill by use of the vibratory milling action; (e) maintaining said mill during said milling at a temperature in the range of 125° to 175° F.; (f) adding stearic acid and gas to partially milled aluminum to replenish stearic acid and oxygen depleted as a result of the milling; (g) removing aluminum flake from the mill at a rate substantially commensurate with the metal particle feed rate; and (h) removing the gas from the mill at a rate substantially commensurate with the gas feed rate.

Claim 24

A method of making aluminum flake in a ball mill comprising the steps of: (a) providing aluminum particles in a mix containing 0.75 to 1.5 wt.% stearic acid; (b) feeding the mix substantially continuously to a vibratory ball mill; (c) supplying a gas containing nitrogen and 8 to 10 vol.% oxygen to the mill, the gas being supplied at a rate not greater than 7 ft 3 /min and having a flow direction in the direction of metal flow; (d) milling the aluminum particles in said vibratory mill for a residency period in the range of 0.5 to 20 hours to form aluminum flake having a surface area in the range of 3.5 to 20 m 2 /gm and moving the particles through the mill by use of the vibratory milling action; (e) maintaining said mill during said milling at a temperature in the range of 125° to 175° F.; (f) adding stearic acid and gas to partially milled aluminum to replenish stearic acid and oxygen depleted as a result of the milling; (g) removing aluminum flake from the mill at a rate substantially commensurate with the metal particle feed rate; and (h) removing the gas from the mill at a rate substantially commensurate with the gas feed rate.