Process and apparatus for roasting of metal sulfide concentrates and/or residues

Patent metadata

Field	Value
Publication number	US-2020010924-A1
Application number	US-201716490988-A
Country	US
Kind code	A1
Filing date	Jun 2, 2017
Priority date	Mar 7, 2017
Publication date	Jan 9, 2020
Grant date	—

Abstract

A process for roasting of metal concentrate wherein concentrate particles are fed into a roaster where they are thermally treated at a temperature in the range of 500 and 1200° C. in a fluidized bed to form a calcine. At least parts of the calcine are withdrawn from the roaster together with a gas stream as a solid fraction. Concentrate particles with a diameter at least 50% smaller than the average diameter of the concentrate particles are separated as small particles and/or particles from the gas-solid-fraction are separated in at least one step as small calcine particles and/or particles are gained in another hydrometallurgical step as other particles. Defined particles are pelletized, whereby at least 80% of the pellets feature a diameter of at least 80% of the concentrate particles average diameter. The pellets are fed into the roaster.

First claim

1 . A process for roasting of metal concentrate, wherein concentrate particles are fed into a roaster where they are thermally treated at a temperature in the range of 500 and 1200° C. in a fluidized bed to form a calcine, at least parts of the calcine are withdrawn from the roaster together with a gas stream as a solid fraction, particles are gained in another hydrometallurgical step as other particles, at least parts of the other particles are pelletized, whereby at least 80% of the pellets feature a diameter of at least 80% of the concentrate particles average diameter and the pellets are fed into the roaster so that the metal concentrate contains at least 45 wt.-% zinc, whereby the concentrate particles' average diameter is between 5 and 40 μm, the metal concentrate contains at least 60 wt.-% pyrite, whereby the concentrate particles' average diameter is between 5 and 90 pm, the metal concentrate contains at least 2 g/t gold, whereby the concentrate particles' average diameter is between 5 and 100 μm the metal concentrate contains at least 15 wt.-% copper, whereby the concentrate particles' average diameter is between 10 and 50 μm, the metal concentrate contains at least 1 wt.-% cobalt whereby the concentrate particles' average diameter is between 5 and 40 μm or the metal concentrate contains at least 100 g/t PGMS, whereby the concentrate particles' average diameter is between 20-100 μm and the other particles are gained in a direct leaching (DL) step or in an Albion process step or in a Pressure Oxidation (PDX) step or in a Biological Oxidation (BIOX) step or in a Pure Jarosite (PJ) process.

2 . The process according to claim 1 , wherein concentrate particles with a diameter at least 50% smaller than the average diameter of the concentrate particles are separated as small particles and pelletized together with the other particles, and/or the small calcined particles are separated in a waste heat boiler, and/or an evaporative cooler, and/or a cyclone, an electrostatic precipitator.

3 . The process according to claim 1 , where particles from the gas-solid-fraction are separated in at least one step as small calcine particles and are pelletized together with the other particles.

4 . (canceled)

5 . The process according to claim 1 , wherein the small particles and/or at least part of the small calcine particles and/or at least parts of the other particles are pelletized such that at least 70 wt.-% are bigger as 500 μm or that at least 70 wt.-% are smaller than 90 μm.

6 . The process according to claim 1 , wherein the amount of sulfur and/or carbon in the concentrate particles is between 0.5 and 60 wt.-% and/or the amount of sulfur and/or carbon in the small particles is more than 20% higher than in the concentrate particles and/or the amount of sulfur and/or arsenic in the small calcine particles is more than 15% higher than the average calcine particles and/or the small calcine particles contain at least 2 wt-% sulfur.

7 . (canceled)

8 . The process according to claim 1 , wherein secondary air is injected into the roaster which is heated to a temperature of at least 200° C.

9 . The process according to claim 8 , wherein at least parts of the calcine are cooled in a fluid bed cooler, whereby the air used as direct and/or indirect cooling medium is used as secondary air and or fluidizing medium in the roaster.

10 . The process according to claim 1 , wherein the small particles and/or at least part of the small calcine particles and/or at least part of the other particles and/or further particles are pelletized by mixing with a liquid binder comprising water or an aqueous solution containing sulfates and/or a low acid concentration.

11 . The process according to claim 1 , wherein the small particles and/or at least part of the small calcine particles and/or at least part of the other particles and/or further particles are pelletized by mixing with further particles.

12 . The process according to claim 1 , wherein downstream of the roaster at least parts of the calcine are leached in leaching solution with an acid content leading to pH value of 2 or less and/or are leached in a cyanide solution or are smelted or introduced into an electric furnace.

13 . The process according to claim 1 , wherein the not recirculated calcine particles are milled and/or grinded.

14 . Plant for roasting of metal concentrate, featuring a roaster for a thermal treatment of concentrate particles at temperatures between 500 and 1200° C. in a fluidized bed to form a calcine and a conduit for withdrawing a gas-solid fraction from the roaster, wherein a hydrometallurgical device for gaining particles as other particles, a pelletizer wherein the particles from the additional hydrometallurgical device are mixed with a liquid binder to form pellets whereby at least 80 wt-% of the pellets feature a diameter of at least 80% of the concentrate particles average diameter and the pellets are fed through a recycling conduit from the pelletizer into the roaster, the metal concentrate contains at least 45 wt.-% zinc, whereby the concentrate particles' average diameter is between 5 and 40 μm, the metal concentrate contains at least 60 wt.-% pyrite, whereby the concentrate particles' average diameter is between 5 and 90 μm, the metal concentrate contains at least 2 g/t gold), whereby the concentrate particles' average diameter is between 5 and 100 μm, the metal concentrate contains at least 15 wt.-% copper, whereby the concentrate particles' average diameter is between 10 and 50 μm, the metal concentrate contains at least 1 wt.-% cobalt whereby the concentrate particles' average diameter is between 5 and 40 μm or the metal concentrate contains at least 100 g/t PGMS, whereby the concentrate particles' average diameter is between 20-100 μm and the other particles are gained in a direct leaching (DL) step or in an Albion process step or in a Pressure Oxidation (PDX) step or in a Biological Oxidation (BIOX) step or in a Pure Jarosite (PJ) process.

15 . The plant according to claim 14 , wherein a fluidized bed cooler is arranged downstream of the roaster.

16 . The plant according to claim 14 , wherein the roaster features an underflow exit conduit to withdraw agglomerations.

17 . The plant according to claim 14 , wherein the plant comprises at least one gas separating device for separating particles from the gas-solid-fraction as small calcine particles pelletizing them in the pelletizer together with the small particles or the other particles.

Assignees

• Outotec Finland Oy

Inventors

• Güntner Jochen
• Charitos Alexandros
• Hammerschmidt Jörg

Classifications

• C22B11/04 Primary

  by wet processes (extraction of metal compounds by leaching in organic solutions C22B3/16; treatment or purification of solutions by liquid-liquid extraction C22B3/26) · CPC title

• C22B11/00 Primary

  Obtaining noble metals · CPC title

• C22B11/02

  by dry processes · CPC title

• C22B1/2406 Primary

  pelletizing · CPC title

• C22B1/10 Primary

  in fluidised form · CPC title