Previously he pointed out, (former) Soviet Union, a considerable portion of the nickel waste disposal in the primary non-ferrous metallurgy enterprises, Hu Urals Nickel Plant. The waste that is sent to the company must first be considered for sorting, mainly by chemical composition. For example, at the Ufalia Nickel United Company, waste containing less than 10% nickel should be selected for remelting in a blast furnace. Depending on their particle size, they are pre-compressed with a fine-grained ore into agglomerates, or they are directly fed into a furnace; waste containing more than 10% of nickel is treated in a converter. Greater than 2% of copper-containing waste preparation can be enlarged with a low copper content of the particles thereof.
The blast smelting of the nickel oxide ore is, by its nature, a reduction sulfidation reaction, that is, in a reducing environment in the presence of a sulphurizing agent. The various components of the charge, including the regenerated non-ferrous metals, are heated by the action of the gas stream, and the components begin to chemically interact with each other and with the gas phase components.
Bronze and slag are the products of interaction. For example, nickel sulfate is heated in a reducing environment, first losing crystal water, then decomposing, or reducing to sulfide. The main reactions are as follows:
NiSO 4 ·7H 2 O=NiSO 4 +7H 2 O ↘
NiSO 4 =NiO+SO 3 (SO 2 +1/2 O 2 ) (1)
NiSO 4 +4CO=NiS(Ni 3 S 2 )+4CO 2 ↗
Similar changes have occurred in nickel carbonate:
NiCO 3 ·6H 2 O=NiCO 3 +6H 2 O ↘ (2)
NiCO 3 =NiO+CO 2 ↗
The reaction takes place in the pre-tropical zone of the furnace.
Some other recycled materials, such as waste batteries, slag containing higher nickel, etc., are also processed in the blast furnace. When the steel shell of the battery is smelted, the iron compound and the nickel oxide ore act as a reducing agent, and the excess iron is dissolved in the sulfide melt. The hydroxides of flake iron and nickel begin to decompose first to form the corresponding oxides. The nickel oxide is then vulcanized and converted to matte, which is transferred to the slag:
NiO+FeS=NiS(Ni 3 S 2 )+FeO (3)
2FeO+SiO 2 =2FeO·SiO 2 (4)
Ferrous sulfide acts as the vulcanizing agent, it enters the charge, in the form of pyrite or add gypsum to be used in the furnace.
The matte obtained by melting in a blast furnace contains Ni 15 to 20%, Co 0.3 to 0.4%, Fe 50 to 60%, and S 20 to 22%. Its output rate is not high, accounting for 5 to 10% of the smelting metal-containing raw materials. The direct recovery of nickel from the ore into the matte is 75-82%; the recovery of nickel from the recycled metal is slightly higher (85-90%).
The second product is slag, and its composition is: Ni 0.15 to 0.20%, FeO 17 to 20%, SiO 2 44 to 46%, MgO 10 to 18%, CaO 12 to 20%, and Al 2 O 3 8 to 12%. The slag is granulated by water and then transported to the scrap yard. In the national economy, slag can be used to produce cement, slag, slag castings and slag wool.
After the gas is cleaned and dedusted, it is discharged into the atmosphere; the recovered flue ash is pressed or sintered to return to the charge. The fuel consumption during smelting is 20 to 30% of the total amount of sinter or agglomerates. In the tuyere area, the unit cross-sectional area productivity of the furnace is 30 to 40 tons / m 2 · day and night.
A considerable part of the raw metal enters the metallurgical enterprise and is processed by a converter. The amount of enriched nickel obtained during the blowing of the native matte is about 40% before being charged into the converter. Untreated recycled waste such as shavings, trimming, scrapped parts, etc. are contacted with the sulfide melt at a temperature of 1250 to 1300 °C.
Chromium , tungsten and molybdenum are transferred into the slag with their respective oxides. According to the above information, a portion of the oxide sublimes and enters the gas. The chromium is actually completely transferred into the slag. The nickel and part of the cobalt present in the recycled material are vulcanized and transferred to the sulfide melt.
FeS+Ni=NiS(Ni 3 S 2 )Fe (5)
FeS+Co=CoS+Fe (6)
In further blowing, a significant portion of the cobalt sulfide is oxidized and transferred to the slag along with iron and other acrobatics.
When disposing of waste in a copper-nickel industrial enterprise, cobalt is forced to remain in the secondary matte, as the process has taken into account the separation of nickel from the nickel when it is electrolyzed. Copper is not an impurity in this case, it is separated from nickel during flotation of secondary matte and electrolysis. Other metals are not expected to be present in the secondary matte.
The secondary water copper obtained from the converter has the following composition (%):
Raw material Ni Cu Co Fe S
Nickel oxide ore 77～80 0.9～1.5 0.5～0.55 0.2～0.3 17～22
Copper sulfide nickel ore 41～49 24～32 0.5～1.0 2.0～3.0 20～22
Using recycled raw materials, the ratio of nickel to copper in copper-nickel double-copper can be changed, which is very important for the next step.
The practice of treating copper-nickel double-copper copper for many years proves that the ratio of Ni:Cu>1 in bismuth nickel secondary ice copper is reasonable.
This ratio is difficult to maintain for many raw materials in many cases, but it is easy to adjust to this ratio in recycled nickel raw materials.
Regardless of whether it is a nickel company or a copper-nickel enterprise, it is necessary to pay attention to the impurity of cobalt when using a converter to treat a higher nickel waste containing cobalt. The cobalt content of nickel double-copper should not exceed 0.5-0.6%. This can be obtained by refining the secondary matte with new matte.
Slag is another product of converter blowing. It contains 0.8-1.2% nickel in the Ural nickel plant, and another nickel plant contains 0.8-1.2% nickel and 0.6-0.8% copper. The content of cobalt in the slag is almost the same, both equal to 0.25 to 0.45%. The content of iron is 47 to 57%, and the content of silicon is 24 to 30%.
The presence of tungsten, chromium and molybdenum in the slag depends on the amount and composition of the recycled metal to be treated, and its content may fluctuate between 0. n% and 3 to 5%. The slag obtained after refining is depleted in a converter or an electric furnace. The purpose of depletion is to extract nickel and cobalt from the slag. In the depleted slag, the nickel content does not exceed 0.2%, the cobalt content does not exceed 0.08%, and the loss of chromium, tungsten and molybdenum is irreparable.
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