Thin layer leaching method

A method for reacting a reagent in solution with particles of solids comprising the steps of:

• forming a layer of particles subject to compaction under their own weight having a thickness in the range of from about one-half to one and 1/2 meters, the layer having a sufficiently small thickness that the permeability of the bottom of the layer is not appreciably less than the permeability of the top of the layer;
• applying a solution containing reagent to the top of the layer;
• percolating the solution downwardly through the layer;
• and
• withdrawing the solution from the bottom of the layer.

A method for reacting a reagent in solution with particles of solids comprising the steps of:

• mixing relatively fine particles of metal bearing ore to be leached with relatively coarse particles essentially inert to the reagent in sufficient quantities that the resulting mixture has more than about 25% by weight particles larger than about 4 mesh;
• forming a layer of particles subject to compaction under their own weight, the layer having a sufficiently small thickness that the permeability of the bottom of the layer is not appreciably less than the permeability of the top of the layer;
• applying a solution containing reagent to the top of the layer;
• percolating the solution downwardly through the layer;
• and
• withdrawing the solution from the bottom of the layer.

A method for neutralizing an acidic solution with particles of solids comprising the steps of:

• forming a layer of particles subject to compaction under their own weight, the layer having a sufficiently small thickness that the permeability of the bottom of the layer is not appreciably less than the permeability of the top of the layer, the particles being selected from the group consisting of limestone, dolomite, calcareous rock and rock containing iron oxide;
• applying the acidic solution to the top of the layer;
• percolating the solution downwardly through the layer;
• and
• withdrawing the neutralized solution from the bottom of the layer.

A process for operating a leaching plant having first and second curing stations and first and second leach pads comprising the steps of:

• leaching a first batch of ore in a thin layer on the first leach pad for first and second days;
• curing a second batch of ore in the first curing station for the first and second days;
• leaching a third batch of ore in a thin layer on the second leach pad for the second day and a third day;
• curing a fourth batch of ore in the second curing station for the second and third days;
• leaching the second batch of ore in a thin layer on the first leach pad for the third day and a fourth day;
• curing a fifth batch of ore in the first leaching station for the third and fourth days;
• and
• continuing the leaching and curing steps in the first and second sets of curing station and leach pad, respectively, on alternating pairs of days.

A method of leaching metal values from ore comprising the steps of:

• mixing a first batch of ore with a strong leaching solution;
• curing the first batch of ore in a first curing station for about two days;
• mixing a second batch of ore with a strong leaching solution about a day after the first mixing step;
• curing the second batch of ore in a second curing station for about two days;
• spreading the first batch of ore in a thin layer in a first leach pad about a day after the second mixing step;
• mixing a third batch of ore with a strong leaching solution about one day after the second mixing step;
• curing the third batch of ore in the first curing station for about two days;
• leaching the first batch of ore for about two days concurrent with the third curing step by percolating leach solution therethrough;
• spreading the second batch of ore in a thin layer on a second leach pad about a day after the third mixing step;
• mixing a fourth batch of ore with a strong leaching solution about one day after the third mixing step;
• curing the fourth batch of ore in the second curing station for about two days;
• leaching the second batch of ore for about two days concurrent with the fourth curing step by percolating leach solution therethrough;
• and
• repeating the steps on alternate days for the first curing station and leach pad and for the second curing station and leach pad, respectively.

A method for leaching metal values from particles comprising the steps of:

• forming a thin layer of particles subject to compaction under their own weight;
• introducing a leach liquid to the top surface of the layer;
• percolating the leach liquid downwardly through the layer for leaching metal values therefrom;
• and
• withdrawing the leach liquid from the bottom surface of the layer;
• and wherein
• the layer has a thickness greater than about one-half meter and a sufficiently small thickness that the yield of metal values from a portion of the layer adjacent the bottom surface is not appreciably less than the yield of metal values from a portion of the layer adjacent the top surface.

A method for leaching a solid comprising the steps of:

• forming a thin layer of particles of the solid on a slope approximately at the angle of repose of the particles, the thin layer being less than about one meter thick;
• spraying a leach liquid on the sloping face of the thin layer of particles;
• and
• recovering leach liquid at the toe of the slope.

A method for leaching metal values from ore particles comprising the steps of:

• contacting the ore particles with a strong leaching solution for a sufficient time to indurate the ore sufficiently to sustain the weight of a layer of ore in the range of from about 1/2 to one and one-half meter thick without appreciable compacting;
• placing the indurated ore particles on a permeable substrate in a layer in the range of from about one-half of one and one-half meter thick;
• and
• percolating liquid down through the layer for leaching metal values from the layer of ore particles.

A method for leaching metal values from particles of ore comprising the steps of:

• forming a first thin layer of particles of ore;
• percolating a first leach solution through the first thin layer and recovering a first effluent;
• thereafter percolating a second leach solution through the first thin layer and recovering a second effluent;
• forming a second thin layer of particles of ore;
• percolating at least a portion of the second effluent through the second thin layer and recovering a third effluent;
• and
• recovering metal values from at least a portion of the first and third effluents.