PELLETIZING AND SINTERING NICKELIFEROUS DUST

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URDIISPG
PELLETIZING AND SINTERING NICKELIFEROUS DUST
Vladyslav M. Sokolov, Dr. Sc., PhD,
vlads_at_visti.com
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Specific grades of ferronickel developed in
Ukraine
Element Grade Grade Grade Grade
Element FN-5Co FN-6 FN-7 FN-8
Ni 14.0-20.0 8.5 3.8 5.3 2.5 4.8
Co 1.5-8.0 0.1- 0.4 0.1 0.4 0.1 0.4
Si 0.05 0.5 3.5 5.0 4.0 8.0
C 0.03 0.5 1.0 2.5 1.3 2.5
Cr 0.08 1.0 2.0 3.0 1.5 4.0
S 0.3 0.1 0.03 0.15 0.15
P 0.05 0.15 0.06 0.18 0.06 0.3
Cu 1.0 3.0 1.00 5.0 6.5 -
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The main objectives

• The object of the investigation is fine waste in
  a form of dust and sludge.
• Particularly it is generated during treatment of
  nickeliferous laterite ore in rotary kiln, during
  the ore smelting in submerged arc furnace and
  during refining the melt in oxygen converter.
• The final goal is working out of the technology
  of recycling environmentally hazardous wastes
  which contains Ni with lower power consumption.

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Current best available practice
Raw charge materials mixture
Calcination
Dedusting
Flue gases
Melting of crude ferroalloy
Metal-containing dust and sludge
Pelletizing
Refining
Processing in oxygen converter to decrease C and
Si content
Landfilling
Slag
Landfilling
Casting of ferroalloy
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Mechanisms of dust formation in the rotary
devices during heating and tumbling

• mechanical decrepitation of the ore as a result
  of tumbling and attrition
• thermal decrepitation during rapid vaporization
  of internal fee and bound water
• loss of fee moisture which function as a binder

Many laterite kiln operations lose over 20 of
the ore input as dust to various particulate
collection devices. As the nickel content in the
ore concentrates in the finer fractions, the dust
may contain a level of nickel that is 50-100
higher than the base ore.
Quotation of the report of FFE Minerals USA at
international laterite Nickel Symposium 2004
Roasting and Smelting
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Methods of fine waste agglomerating (compacting)
Extrusion
Briquetting
Pelletizing with rotary drum or disc pelletizer
water additions up to 30 need re-drying low
density low strength
with cement binder
high green strength up to 20 moisture addition
sensitivity of the extrusion strength to dust
properties
sensitivity of the compactions strength to dust
properties
adds considerable cost require several hours of
curing for strengthening before thermal treatment
non applicable in our case
Any agglomerate produced by the above methods is
not sufficiently strengthened during its
processing in rotary kiln
W e o f f e r
Using generated slag as a charge component
Pelletizing
Treating the pellets by crude FeNi
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Proposed approach simple and effective
Raw charge materials mixture
Calcination
Dedusting
Flue gases
Melting of crude ferroalloy
Metal-containing dust and sludge
Landfilling
Molten crude ferroalloy
Pelletizing
Pellets treating
Refining
Processing of pelletizing with exothermal
oxidizing of Si
Processing in oxygen converter to decrease C and
Si content
Slag
Ferroalloy with low C and Si
Metallized smelted slag
Landfilling
Casting of ferroalloy
Additional heating
Extraction of beads
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Recycling Dust and Sludge of Ferronickel
Production
Pellets up to 10 of pouring melt
Molten crude ferronickel
90 of Ni from pellets
10 of Ni from pellets
Molten crude ferronickel for converting
Semi-finished product for following smelting
laboratory experiments
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The ways from waste to metal
waste to the agglomerated form (ready for
following metallurgical application)
high quality agglomerate
pellets
waste
processing by liquid metal
pouring
heating
processing
valuable semi-finished product
slag
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Basic Characteristics of the Portable ESCR Furnace
Volume of the furnace working chamber, l Volume of the furnace working chamber, l 30
Melting capacity, kg Melting capacity, kg 70
Average productivity, kg/h Average productivity, kg/h 20
Supply-line voltage, V Supply-line voltage, V 380
Total power, kVA Total power, kVA 130
Re-melting current, not more than, ? Re-melting current, not more than, ? 3000
The Installation dimensions, mm length width height 2000 2300 2200
Mass, kg Mass, kg 2450
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Results of ESCR of different types waste charge
Type of charge Extraction of Ni
Roasted lateritic ore after rotary kiln 1,26
Pelletized dust 1,68
Slag from treatment of pelletized dust by crude ferronickel 3,12
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Schematic diagram of an iron-ore sintering plant
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Sintering of dust and sludge
Equipment for trials
drum pelletizer
sintering pot
the unit for mechanical strength test
the specific rotating drum for rate of durability
determination
Produced high quality sinter with perfect
mechanical properties
Yield of the sinter fraction lt5mm is about 15
on the average
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The sinter almost fully smelted macroporous
material consisted of large (up to 30 mm) joined
particles
1 silicate base 2 beads 3 pyroxens 4
magnesia olivine 5 spinels 6 silica

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The sinter processing
The initial dust composition
Ni Fe SiO2 CaO MgO Al2O3 C S
2.79 24.5 37.1 1.05 15.3 2.9 0.9 0.12
The sinter composition
Component Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass Chemical composition, mass
Component Si P S Ti Mn Fe Co Ni Mg Al Ca Cr O
The average composition of the silicate base 21.4 - - - 0.99 21.8 - 1.1 6.5 2.9 5.1 0.12 40
Olivines 17.7 - - - 0.73 24.1 - 3.9 15.2 - - - 38
Spinels - - - 3.3 - 54.9 0.08 2.2 2.1 1.6 - 6.3 30
Beads - 0.14 2.2 - - 22.6 0.86 74.2 - - - - -
0.07 0.22 3.5 - - 4.4 0.33 91.4 - - - - -
- 0.21 19.8 - - 2.3 - 77.7 - - - - -
The final metal composition
Ni Fe Si Mn Co Mo P S
22.89 24.5 0.23 0.13 9.4 1.4 0.16 1.6
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The results of the balance melts
Type of product to be processed calcine from PIFM dust in a form of pellets the sinter
Metallic part 8,5 10 10,5
Content of Ni in the reduced metal 14,81 10,75 22,89
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Sintering equipment and systems
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We propose to set a sintering plant that includes

• Stockyard with bunkers for dust, coke breeze and
  the other additions.
• Conveyers for transportation of the feedstock to
  the drum-mixer.
• Conveyer for transportation of the mixer to the
  pelletizer.
• Conveyer for transportation of the pellets to
  the sinter strand. Sinter hoods for igniting of
  the charge. Aspiration system for exhaustion and
  cooling operation.
• Crushing and screening of the produced sinter.
• Storing of the sinter for following
  transportation to the furnace.

The total operating area is 750 m2, the height 25
m. The equipment for environmental protection
should be considered later
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The price of the basic technological equipment
Drum-mixer 340, 000 Euro
Pelletizer 340, 000 Euro
Sintering strand with two loading units, two sinter hoods and coolers of sinters 3 112, 000 Euro
Crusher 325,000 Euro
Vibroscreen 40,000 Euro
TOTAL 4 157,000 Euro
The controlling equipment and starting-up and
adjustment are not included
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Recycling dust and sludge of ferronickel
production

• Mostly all Ni from the waste is extracted
• As the result the ratio between ferronickel fine
  waste and ferronickel product is sufficiently
  reduced
• The necessary prerequisites for introduction the
  technology into practice have been created