Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B23/00—Obtaining nickel or cobalt
  • C22B23/02—Obtaining nickel or cobalt by dry processes
  • C22B23/021—Obtaining nickel or cobalt by dry processes by reduction in solid state, e.g. by segregation processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
  • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
  • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
  • B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B5/00—General methods of reducing to metals
  • C22B5/02—Dry methods smelting of sulfides or formation of mattes
  • C22B5/12—Dry methods smelting of sulfides or formation of mattes by gases

Definitions

• the present invention relates to a method for producing a fine, low bulk density, metallic nickel powder.
• Canadian application No. 2,418,063 teaches how to produce an active nickel powder by reducing a nickel chloride containing salt having a high surface area with hydrogen gas at a temperature above 300 0 C, and how to rapidly convert such active powder to nickel carbonyl.
• this patent application does not address the deleterious issue of particle agglomeration during the production of active nickel powder.
• US Patent 3,914,124 teaches the use of at least one additive selected from the group consisting of "calcium oxide, magnesia or compounds that are heat decomposable thereto" (abstract), to create an anti-agglomerating coating on a substantial portion of the particles to minimise sticking while reducing nickel oxide.
• the process disclosed requires very high temperatures to assure a low volatile impurity content.
• Canadian Patent 2,204,525 teaches the use of an organic dispersant such as gelatin and/or bone glue as an anti-agglomerating agent, as well as of a spheroid-promotion agent such as anthraquinone.
• an organic dispersant such as gelatin and/or bone glue
• a spheroid-promotion agent such as anthraquinone.
• the process disclosed results in the formation of a high density nickel powder, as opposed to low density nickel powder.
• US Patent 2,948,525 teaches the use of a kiln with a completely continuous oxide film, such as aluminium oxide, which is irreducible at the temperature used for reduction of nickel compounds, so as to eliminate sticking of the nickel powder to the kiln walls.
• this patent does not solve the problem of inter-particles sticking and agglomerating.
• the present invention seeks to meet this and other needs.
• a fine, low bulk density, metallic nickel powder can be produced by treating reducible nickel salts with a hydrogen- containing gas, at temperatures ranging from about 300 0 C to about 500 0 C, while the extent of movement and the average kinetic energy of the freshly produced metallic nickel particles are minimised. This method has been found to significantly reduce formation of nickel agglomerates.
• the present invention relates to a method of producing a fine, low bulk density nickel powder, comprising:
• the bed of furnace charge being moved gently so as to minimise formation of hard agglomerates and thereby obtaining a fine, low bulk density nickel powder.
• the present invention also relates to a method of producing a fine, low bulk density nickel powder, comprising:
• the static bed of furnace charge being shallow so as to allow penetration of reducing gas into the bed and minimise formation of hard agglomerates, thereby obtaining a fine, low bulk density nickel powder.
• Figure 1 is a graph illustrating the effect of reducing the rotation rate of a kiln having an internal diameter of 10.2 cm on the quantity of metallic nickel powder passing various screens (size fractions are indicated in microns);
• Figure 2 is a graph illustrating the effect of varying the rotation rate of a kiln having an internal diameter of 10.2 cm on the quantity of metallic nickel powder passing through a 65 mesh screen (210 microns);
• Figure 3 is a graph illustrating the effect of varying the rotation rate of a kiln having an internal diameter of 10.2 cm on the quantity of metallic nickel powder passing through a 100 mesh screen (149 microns);
• Figure 4 is a flowchart of a preferred embodiment of the present invention.
• Figure 5 is an electromicrograph of a dry free-flowing powder of nickel carbonate and nickel hydroxide used as a feed in Example 1 , and as typically used in the method of the present invention (AMRAY Scanning electron microscope, x500 magnification); and
• Figure 6 is an electromicrograph of a fine, low bulk density metallic nickel powder as obtained according to the method of the present invention (AMRAY Scanning electron microscope, x500 magnification). DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
• the present invention relates to a method for producing a fine, low bulk density, unagglomerated or friable, metallic nickel powder by reducing, in a hydrogen containing gas, a furnace charge that is either static or moved gently so as to minimise the average kinetic energy of these freshly reduced particles.
• particle designate any small piece or part of a flowable material, such as a powder.
• agglomerate refers to a group of individual particles sticking together to form either a soft or hard lump.
• the term "fine” means that at least about 45% of the powder would pass through a 100 mesh (149 microns) screen, with essentially no remaining hard agglomerates in the +100 mesh fraction.
• the term "low bulk density” means a bulk density of 4 g/cc or less.
• nickel powders obtained by the method of the present invention have a bulk density between about 0.5 and about 2 g/cc.
• nickel powders obtained by the method of the present invention have a bulk density between about 0.5 and about 1.6 g/cc.
• the term “shallow” defines a depth of powder charge that would allow the penetration of reducing gas into the bed. Usually, such static shallow bed is about 2.5 cm deep or less.
• the screening measures referred to in this application were performed on a well-known Ro-TapTM machine, in which the screens are shaken and tapped.
• the screening period used was usually 20 min.
• the method according to the present invention utilizes either a static or slowly moving furnace charge.
• the method itself can be performed either continuously or batch- wise.
• the reduction temperature ranges from about 300 0 C to about
• 500 0 C preferably from about 350°C to about 450 0 C.
• the reducing gas contains at least
• the hydrogen containing gas is preheated before entering the kiln.
• the feed of reducible nickel salt is calcinated in a nitrogen or other inert gas atmosphere at a temperature ranging from about 300 to about 350 0 C. This is done in either the first compartment of the furnace or in a separate furnace.
• Such calcination of the feed drives off carbon dioxide gas from the nickel carbonate in the v feed and thus allows separate scrubbing and removal of carbon dioxide. This simplifies the cleaning of the off-gas from the reduction step and allows the recycling of unused hydrogen.
• FIG. 4 One of the preferred embodiments of the present invention is illustrated on Figure 4.
• the dry free flowing powder of reducible nickel salt (1) is calcinated in a first furnace in presence of nitrogen gas (2).
• the off-gas of calcination (4) essentially contains CO 2 , CO, H 2 O and N 2 .
• the hot calcine (3) is then transferred into a second furnace, namely the reduction kiln, so as to form a bed of furnace charge.
• H 2 gas (5) is advantageously passed into the static or slowly moving bed of furnace charge, and an excess of H 2 is advantageously used.
• Such a process allows obtaining a fine, low bulk density nickel powder (6). Thanks to the separate calcination step, the off-gas of the reduction kiln only contains H 2 and H 2 O, which allows an easy H 2 recycling.
• composition of the feed of reducible nickel salt used in the method of the present invention may of course influence the final bulk density and fineness of the nickel powder product.
• the bulk density of the nickel powder product increased as the total amount of inert impurities in the feed material decreased.
• Inert impurities are typically various amounts of carbonate/chloride/sulphate salts of sodium/magnesium/calcium. This is illustrated in Table 1 below.
• the bulk density of nickel powder product decreased from 1.2 g/cc to 0.5 g/cc as the total amount of inert impurities increased from about 10 wt% (well-washed nickel carbonate) to about 30 wt%
• the feed composition also has an influence on the fineness of the metallic nickel powder product, as illustrated in Table 2 below.
• Table 2 shows that, as the degree of washing of the nickel carbonate decreases, and therefore the inert impurity content increases, the nickel powder obtained according to the process of the present invention becomes much finer. Indeed, at least 99% of the final product obtained from a poorly washed nickel carbonate feed (about 30 wt% inert impurities) pass through a 100 mesh screen.
• the reducible nickel salts used in the method of the present invention are preferably nickel carbonate, nickel oxide, nickel hydroxide, nickel oxalate.
• nickel carbonate nickel oxide
• nickel hydroxide nickel oxalate
• any other fine, low density nickel compound that is reduced to a metallic state in hydrogen gas below 500 0 C can also be used.
• nickel chloride may be used.
• nickel chloride either hydrated or not, or other reducible nickel salts that happen to melt or become sticky below 500 0 C, can be used as feed in the method of the present invention only when used in combination with at least another reducible nickel salt of the above category, such as the preferred cited salts.
• Peripheral velocity internal diameter x Pi x rotation rate (cm/min) (cm) (rpm)
• the bulk densities of nickel powders produced in the rotating kiln used in this example varied between 0.46 and 1.58 g/cc, as shown in Table 3 below.
• EXAMPLE 3 Fine, low bulk density nickel powders were prepared according to the method of the present invention in a rotating kiln with an internal diameter of about 61 cm (24 inches). In a continuous process, 7 to 8 kg per hour of nickel carbonate were fed to the kiln. The reduction temperature was 350 to 400 0 C in the first half of the kiln and 450°C in the second half of the kiln. Hydrogen and nitrogen gases were fed at 85 and 42.5 lpm, respectively, in the kiln rotating at 0.125 rpm, corresponding to a peripheral velocity of 23.9 cm/min. The residence time of the feed in the kiln was about 20 hours.
• peripheral velocity used in the kiln having an internal diameter of 61 cm was higher than that used with the smaller diameter kilns (examples 1 and 2) so that an acceptable economical powder production rate could be achieved.
• nickel powder was produced using two passes through the kiln. During the first pass, preheating in nitrogen gas was used to drive off carbon dioxide from the nickel carbonate in the feed material. In the second pass through the kiln, the furnace charge was reduced with hydrogen gas to a low bulk density nickel powder.
• Typical kiln conditions for the preheating step were as follows: kiln rotation rate 0.22 rpm, kiln slope 0.014 feet/foot, kiln shell temperatures feed end: 330 0 C, product end 450 to 460 0 C, nitrogen gas flow 100 litres per minute, CO2 in off gas 22 volume %, feed rate 16 to 17 kg/hour.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

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• 2005
  • 2005-07-20 BR BRPI0518440-1A patent/BRPI0518440A2/pt not_active IP Right Cessation
  • 2005-07-20 AU AU2005306521A patent/AU2005306521A1/en not_active Abandoned
  • 2005-07-20 EP EP05764274A patent/EP1812611A4/en not_active Withdrawn
  • 2005-07-20 WO PCT/CA2005/001144 patent/WO2006053418A1/en active Application Filing
  • 2005-07-20 JP JP2007541593A patent/JP4961348B2/ja active Active
• 2011
  • 2011-12-09 JP JP2011269857A patent/JP5650632B2/ja active Active

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