Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C3/00—Removing material from alloys to produce alloys of different constitution separation of the constituents of alloys
• • 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

Definitions

• the fine materials contain a substantial proportion of nickel, i.e., approximately 40 percent or more nickel, it is important that a means be provided whereby the nickel content of the fines can be recovered in usable form. It is to the solution of this problem that the present invention is directed.
• the present invention is directed to a method for recovering nickel from fine alloyed material, i.e., materials having a particle size not greater than about onequarter inch and containing about percent to about 25 percent magnesium, up to about 50 percent silicon, e.g., about 25 percent to about 35 percent silicon, up to about 12 percent iron and the balance essentially nickel, e.g., at least about 40 percent nickel.
• the aforementioned fine materials are mixed with proportioned amounts of powdered iron oxide, e.g., magnetite (Fe O hematite Fe,o, or mill scale, an alkali metal nitrate, silica and fluorspar. The mixture is charged into a refractory container and ignited.
• the mixture reacts exothermically, principally by oxidation of the magnesium content in the fine materials, and produces a melt comprising a magnesia-containing slag and metal.
• the metal contains a major proportion of the nickel and a substantial proportion of the silicon contained in the fine material while the slag contains substantially all of magnesium (as MgO) and a proportion of the silicon (as SiO contained in the initial fine materials.
• the function of the sand and fluorspar additions in the original mixture is to form a slag which is fluid at the temperature generated so that ready separation of metal and slag is accomplished.
• the powdered ingredients of the mix have particle sizes not exceeding about 8 mesh, e.g., about 100 mesh to about 8 mesh, as referred to the Tyler Standard Screen (TSS) mesh size.
• the proportioning of iron oxide, e.g., magnetite, hematite, etc., to magnesium contained in the fine materials should be such that the iron oxide exceeds in weight the amount of magnesium in the fines. It is also important that the alkali metal nitrate present in the charge exceed in weight the magnesium content of the fines.
• the weight ratio of iron oxide to magnesium in the fines should be at least about l.25: l and the weight ratio of alkali metal nitrate to magnesium in the fines should be at least l.4:l.
• the proportion of silica in the charge is also related to the proportion of magnesium in the fines being treated.
• magnesia is a very high melting point refractory material and it is necessary to provide sufficient silica in the initial charge to insure the formation of a fluid slag with the magnesia generated.
• the fluorspar addition in the charge is also helpful in this connection.
• iron oxide FeO
• the molar ratio of magnesia to silica plus FeO in the resultant slag not exceed about 1.3:1, i.e., be approximately 1:1 in order to assure that a fluid slag will form.
• the alkali metal oxide e.g., sodium oxide or potassium oxide, resulting from decomposition of the alkali metal nitrate also acts to improve the fluidity of the slag formed. For this reason, the alkali metal nitrates are employed rather than ammonium nitrate.
• EXAMPLE 1 Three ten kilogram charges were prepared comprising about 6.5 kilograms of nickel-magnesium-silicon alloy fines having a maximum particle size of about 8 mesh and containing about 45 percent nickel, about 31 percent silicon and about 14 percent magnesium, mixed with 1.5 kilograms of powdered magnetite (50 mesh) and 1.3 kilograms of sodium nitrate crystals. Five percent by weight of the total charge comprised sand (silica) having a particle size of abut 60 mesh and about two percent by weight of the total charge comprised powdered fluorspar mesh). Each charge was placed in a brick-lined vessel and ignited by means of an aluminum-sodium nitrate fuse. The reaction took place very rapidly to form metal and slag which separated to form a metal button" with an overlying slag layer. The metal buttons from the three runs were analyzed for nickel, silicon, iron and magnesium with the following results.
• a 1,100 kilogram charge was prepared which contained 650 kilograms of alloy fines containing about 45 percent nickel, about 30 percent silicon and about percent magnesium.
• the fines were mixed with 140 kilograms of magnetite having a particle size of about mesh, about 130 kilograms of sodium nitrate having a particle size of about 20 mesh with five weight percent of silica sand having a maximum particle size of about 40 mesh and about two weight percent of fluorspar having a particle size of about 200 mesh.
• the mixture was ignited in a brick-lined container and reacted exothermically to produce nickel-containing metal and a magnesia slag.
• the entire metal remained in the molten state for about 180 minutes thereby assuring good metal-slag separation.
• the metal ingot was readily separated from the slag with a sharply defined demarcation between the metal and slag phases.
• a nickel recovery in the metal phase of 99 percent was achieved.
• EXAMPLE III A charge comprising six kilograms of fines having the composition of Example I, about one kilogram of a nickel oxide in the form of high temperature nickel oxide granules produced by fluid bed roasting nickel sulfide at a temperature above the fusion point of nickel sulfide, about one kilogram of magnetite, about l.2 kilograms of sodium nitrate, about three weight percent of silica sand and about one weight percent of fluorspar was prepared and ignited in a brick-lined vessel.
• the maximum particle size of the ingredients in the charge was 8 mesh TSS. Excellent slag-metal separation was obtained as a result of the reaction and a nickel-silicon-iron alloy ingot weighing about five kilograms and containing 58.6 percent nickel with a nickel yield of 82 percent was obtained.
• the present invention affords an extremely expeditious way to recover nickel from nickel-magnesium-silicon alloy fines. High recoveries of nickel result and a useful product is yielded directly. Thus, the nickel-containing ingot which results is readily melted in conventional equipment including arc furnaces, induction furnaces, and the like, without encountering the problems which made the initial nickel-containing fine material almost impossible to treat in such conventional furnaces.
• nickel-magnesium alloy fines containing about l0 percent to about 25 percent magnesium, up to four percent carbon and the balance essentially nickel may be employed.
• Such alloys are disclosed, for example, in U.S. Pat. No. 2,529,346, particularly alloys containing about 10 percent to about 20 magnesium, about 1.25 percent to about four percent carbon and the balance essentially nickel. it is to be understood that such alloys and nickelmagnesium-sihcon alloys are included in the term nickelmagnesium alloys as used herein and in the appended claims.
• the method for recovering nickel from nickel-magnesium alloy fines containing about 10 percent to about 25 percent magnesium and up to about 50 percent silicon which comprises mixing said fines with powdered iron oxide, an alkali metal nitrate, magnesium-fluxing amounts of silica and fluorspar, with the weight ratios of iron oxide and of alkali metal nitrate to the magnesium content of the fines in the mixture each exceeding unity, and then igniting said mixture to melt the constituents thereof and produce a nickel-containing metal melt and a fluid magnesia-containing slag wherein the molar ratio of magnesia to silica plus FeO does not exceed about 1.3:1 whereby high recovery of nickel from the fines is achieved in the metal melt and whereby good metal-slag separation is obtained.
• alloy fines contain at least about 40 percent nickel.
• alloy fines contain about 25 percent to about 50 percent silicon.

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Citations (6)

• 1969
  • 1969-12-31 US US889726A patent/US3647419A/en not_active Expired - Lifetime
• 1970
  • 1970-12-07 ZA ZA708255A patent/ZA708255B/xx unknown
  • 1970-12-16 GB GB59773/70A patent/GB1300289A/en not_active Expired
  • 1970-12-22 JP JP45115297A patent/JPS4926806B1/ja active Pending
  • 1970-12-30 FR FR7047303A patent/FR2074468A5/fr not_active Expired
  • 1970-12-30 DE DE19702064587 patent/DE2064587A1/de active Pending

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