OA16966A

OA16966A - Process to produce manganese pellets from non-calcinated manganese ore and agglomerate obtained by this process.

Info

Publication number: OA16966A
Application number: OA1201100029
Authority: OA
Inventors: Washington Luiz Mafra; João Batista Conti de SOUZA
Original assignee: Vale S.A.
Priority date: 2008-07-25
Filing date: 2009-07-27
Publication date: 2016-02-26

Abstract

It is described a manganese pellet production from non-calcinated manganese ore, comprising the following phases: (a) ore size preparation through ore classification by function of particle size, smaller or equal to 1 mm particles being maintained from the ore particle fraction process so as to have a smaller or equal to 1 mm size, as well as the comminution of these particles; (b) flux addition; (c) agglomerant addition; (d) pelletizing resulting in crude pellets; and (e) thermal processing through crude pellet drying, pre-heating and heating.

Description

PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE AND AGGLOMERATE OBTAINED BYTHIS PROCESS.

Application field

This is a manganèse pellet production process, based on non-caldnated manganèse ore. The invention-obtained product (manganèse ore pellets) is used in ferroalloy production (Fe - Mn, Fe - SI - Mn) in electrlc fumaces, in Blast Fumace manganèse high-grade pig Iron and/or . as alioy element In producing spécial steels.

State of Art

Manganèse .has major importance In steeimaking. Approximately 90% of world manganeso output is earmarked for steeimaking processes as ferroalloys.

Brazll holds manganèse ore reserves in the states of Parà, Mato Grosso and Minas Gérais and these ores differ in their géologie formation.

Much fine Is generated In ore extraction at the mines and in the manganèse processing stations. Due to its grain size, such material has no direct use either In fermalioy-maklng electric furnaces or In other fumaces. They are harmful to bed permeability, redudng plant productivity and increasing power consumption, In addition to environmental problème.

Manganèse ore producers - especially those generating much fins - relentiessly pursue alternatives to Increase the use of such ores. Among tachnologlcai alternatives under considération are fine agglomération via sintering, peiietizing and briquetting.

The manganèse sintering line Is well established. This ore displays sintering-adequata behavior and produces appropriate sinter to ba used In réduction elactric fumaces - especially In local use - inasmuch as sinter lacks enough mechanical résistance to support excessive handling and long-djstance hauling.

Some studies hâve been conducted In cold agglomération via briquetting and peiietizing, but such studies hâve not been successful due to major pmblems In the physical end metallurglcal quaiity of the agglomérâtes produced.

Hot manganèse pellet-maklng'has been studied before by companies and research centers. These studies showed that post-bum pellets are very brittla due to intensive crack génération. In ali Iikelihood, this is due to much fire-caused loss of ore and to transformations in the manganèse oxide phase. These facts hâve led to including preliminary phases In ore thermal processing In the production chain, almed at making feasible the production of high physical quaiity Mn pellets.

The most common manganèse pellet production process uses previously-caldnated manganèse ore, In a fluldized bed redudng atmosphère. This process involves manganèse ore thermal treatment following pelletizing' and raw peitet buming. This thermal treatment, also known as reducing calcination, aims malnly at generating magnetite and at facilitating Iron élimination through magnetic séparation, leading to ore enrichment A side effect of this thermal treatment is the decomposing of manganèse superior oxides which Interfère with manganèse pellet buming In treditional production processes (Grate Kiin and Traveling Grate). Hence, the conventional manganèse peitet production route Includes, in addition to prevlous calcination In a fluidized fumace atmosphère, the phases of milling, fîltering, magnetic séparation, peiietizlng and buming In Traveling G rate-type fuma ces.

. The technique’s major hurdle to be overcome Is the dlfficulty In obtaining physicaily* adéquate manganèse pellets, when they are produced from non-calcinated ore. In the process of buming manganèse gross pellets obtained from non-calcinated ore, many defects occur in the pellet structuré, such as cracks and fissures which slgnificantly reduce résistance to compression. In extreme cases, this could lead to full pellet structurai détérioration, a.k.a. spalling. Such phenomenon Is due to excessive steam génération in the drying and pre-heating phases, caused by water évaporation and décomposition of manganèse superior oxides. In cases wherein pellets hâve no adéquate poroslty, the steam generated créâtes Internai tensions In the pellet structure which are sufficient to make It brittie or even destroy it. A physlcaliy Inadéquate pellet may generate excessive fines when handled, In hauilng and/or during Infumace réduction. This génération of fines may lead to product loss, if there Is sieve screening prior to fumace or lead to poor material performance during réduction, due to loss of bed permeability.

Although important for steelmaklng, production of manganèse ore pellets has been little studled so far, and few papers hâve been publlshed.

. The document JP 001040426 deals with obtelning pellets from pre-reduced manganèse ores.

The document LIA 1684711 deals with obtaining manganèse Iron from poor-quatity manganèse ores.

The document US 4273575 deals with Iron ore fines or manganèse fines with particles under 150 microns, converted Into sphères whose maximum size tops off at 6.0 mm, by adding agglomérants, followed by pelletizing end thermal treatment at 300 °C.

The document JP 57085939 deals with raw material for iron-manganese production, entailing manganèse ore fines undergolng addition of 7.0 % of Portland-type cernent agglomérant, and It may reçoive 7.0 % to 10.0 % water addition. Pellets are then cured at a time Interval which can range from three days to one week.

ICOMI - Industrie e Comérdo de Mlnérlos do Amapâ built and operated a pelletizlng plant aimed at using manganèse ore from its own mine. This plant was developed by the USA's Bethlehem Steel Corporation (BSC).

This plants monthiy production capacity was 20,000 tons.

Physlcal properties of manganèse pellets can be compared to those obtained/known in iron ore pellets.

Plant management and operation were handled by ICOMI and technicai assistance was provided by BSC.

Ore from Serra do Navlo Mine (SNV) was a manganèse oxide ore (65% weight) displaying the following formation:

Cryptomelane	KMneOl6.H2O	Prédominant component
Hausmanite	Mn₃O₄	ln lesser proportion
Alumina	Aluminum silicate	20%
Iron ore oxide	FeO(OH) Goelhite	15%

FIGURE 1 shows the process flowchart for ore processing to feed the redudng calcination phase (Roaster) used by ICOMI.

Products from ICOMI's processing plarjt dlsplayed the following features:

Coarse	75-13 mm	washed screened	and sleve	48, 5% Mn
Gauged	13-8 mm	washed screened	and sleve	46% Mn
Small	8 mm - 20 Mesh	Rake-type classifier	43% Mn
Fine	20-100 Mesh	hydrocyclone underflow	31% Mn
Sûmes	<100 Mesh	hydrocyclone overflow	16% Mn

For purposes of ICOMI pellet production, In the desired grain size, the system was a mix of 75t small and 50t fines, or 60% and 40% respectively. This mix (8 mm to 150 Mesh grain size) was then fed into the fluldlzed bed fumaca (Roaster), which is used for calcination ln a redudng atmosphère. The chlef objective at this phase was to transform iron ore content from Hématite to Magnetite. Magnetite removal was made possible by magnetlc séparation. This Increases the manganese/iron ratio, that is, it enriches the manganèse ore. Furthermore, It has a side effect of caidnating the ore, which ensures that breakdown of superior Mn oxides does not occur during the pellet-bumlng process.

ln order to pelletize the Mn ore - concentrated and caldnated - ICOMI used bentonite as agglomerating agent, adding 20 kilograms par ton of ore (2.0%). Résistance to compression by the pellets produced was ln the order of 250 kgf per pellet

FIGURE 2 shows ore processing during reduclng calcination up to pelletizing

The pelletizlng disk was made with step-type levels, aimed at Increasing résistance time 5 of the matériel in the disk. This was conducive to better formation and superior finlshing of crude pellets. ♦

FIGURE 3 shows the schematic flow of crude pellet drying, pelletizing and screening. .

A Traveling Grate-type fumace was used by ICOMI ln the bum phase (see FIGURE 4 drawing representing pelletizing bum furnace). FIGURE 4 caption is In TABLE 1 herein below:

Description	Caption
Crude pellets	(D
Upwards drying	(2)
Downwards drying	β)
Pre-bumlng	(4)
Buming -	(5)
Post-bumlng	(6)
Cooling	t7)
PE	(8)
Bumt pellets	ffî

TABLE 1 - Figure 4 Caption

TABLE 2 below Indicates spécification of ICOMI products:

Product	Size	Chemical Breakdown (% weight)	%<6mm
(mm)	Mn	Fe	SIO2	AI2O 3	Mn/Fe	K2O+Na2O	P
Coarse	75-13	48,5	5,8	2,5	5.2	8/1	2.0	0,09	15
Gauged	13-8	48,0	6,0	2.0	5,0	8/1	-	-	-
Small	8-20#	43,0	8,0	5,0	7.0	5/1	1.5	0,10	100
Fines	20#- 100#	31,0	10,0	14,0	12.0	3/1	-	-	-
Sûmes	<100#	16,0	14,0	25.0	30,0	1/1	-	-	•
Pellet	20-8	55,1	6.1	5,2	7,2	9/1	1.1	0,09	10

TABLE 2 - ICOMI Products’s Spécifications . ln summary, iCOMI’s pelletizing process demande a reduclng calcination phase, followed by magnetic séparation as an alternative to Increase the Mn/Fe ratio in the ore, making 15 It possible to reduce the dégradation effect brought about by the chemical processing of pellets. Foilowing this phase, the ore underwent wet mllling, was classified by hydrocyciones, subject to thlckenlng, homogenlzing, filtering and ore drying, prior to its pelletizlng phase.

Objectives of the invention * .

*

It is an objective of this Invention to produce pelleta with manganèse ore fines, eilmlnating previous ore calcination and replacing the phases of milling, thickenlng, homogenlzlng, filtering and drying with natural relier press comminution.

The product obtained has pre-defined chemical breakdown and physical features, such as high résistance to compression and to wearing (abrasion), In order to withstand load-andunioad handling, long distance hauling and processing In steelmaklng fumaces.

This Invention downplays the catastrophlc effect of pellet dégradation, through:

- · adéquate control of ore graln-size distribution; .

' · knowledge of transformation mechanisms phases, thus Increasing the température the ore Is subject to (vide Table 3):

· élaboration of an adéquate thermal cycle for purposes of controlling the buming phase.

TEMPERATURES	REACTIONS
560 - 630 *C	4 MnOî (c) at 2^Λη₂Ο₃ ( c ) + O₂ stable Pirolusite Crlptomelane Reaction
840 - 900 *C	2 KMnaOu ( c) at 6 Mr^Oj ( c ) + 3 O_a + KîMn«O_e (c) Crlptomelane Partridgelt Potassium Permanganate
900 -1020 * C	3 Mn_aO₃ (c) at 2 MnO. Mn₂C>3 (c) + % O₂Hausmanite Partridgelt 2 KjMr^Oe ( c ) at 4 Mn₂O₃ ( c ) + O₂ + 2KïO ( llq ) Potassium Permanganate 2 K₂O ( liq ) + A!₂O₃ ( c ) + 2 SiO2 ( c ) at 2 KAISIO, ( c ) + 2 o₂

TABLE 3 -Temperature-dlctated manganèse ore reactions

Advantagos ofthe Invention

A new process was developed to obtain manganèse peliets from prevlously noncalcinated ore. This process has some advantages, among them:

- to allow the obtention of a product with pre-set/known chemical breakdown; greater mass balance précision;

- to allow a reduction/eiimination of heavy éléments through their recovery via gas processing system;

- to allow the obtention of manganèse pelleta displaying adéquate mechanical résistance to withstand long-distance haullng, handllng and dégradation during its use In métallurgie reactors, generating less fines In ail thesa phases;

- significantiy reduced operating cost vis-à-vis conventional process cost;

- to allow the Improvement of metallurglcal reactors performance. Increased productivity of alloy Iron fuma ces by function of a more homogeneous particle size and better load permeabillty;

- to allow the obtention of a more homogenous product In terms of chemical composition, physlcal and metallurglcal qualifies of Its components - production of loads almed at the fabrication of alloy irons, pig Iron or as added element for the fabrication of spécial . steels;

- to allow the reuse of fines generated during extraction, handllng/beneflciation end transportations - maximizatlon of reserves;

- to allow the réduction of environmental liabilltles;

- to allow the recovery of dam-related materials - reuse of tailings. Tum fine ore consldered waste into reserves:

- to allow the treatment of residues at their very generating source, thereby reducing environmental liabilltles as well as fabrication costs as a resuit of reduced raw material cost by vlrtue of their decreased value and that of obtained substitution ratios;

- to allow .the anticipation of solutions in the case of more severe environmental restrictions In Europe;

- to allow a lower moisture grade product, thus reducing frelght costs with a metalllc-richer product;

. - to allow the Introduction of a new and higher aggregate value product In the market;

Summarized description of the Invention

Manganèse.agglomérâtes showing Improved mechanical strength were developed, as well as their respective production processes through comminuted manganèse ore agglomération with no prevlous calcination, using hot pelletizlng, comprising the following phases:

(a) ore slza préparation through/ore classification by function of particle size, smaller or equal to 1 mm particles being maintained from the ore particle fraction process so as to hâve a smaller or equal to 1 mm size, as well as the comminution of these particles;

(b) addition of flux;

(c) addition of agglomérant;

* (d) pelletizing resulting ln crude pellets; and (e) thermal processing through drying, pre-healing and crude pellet heatîng.

Summarized description of the drawings

An élabora le description of this présent Invention Is presented herelnafter based on an execution example depicted by drawings. Pictures and photos show:

FIGURE 1 - shows ore treatment process flowchart for the reducing calcination phase feed ' (Roaster) used ln the prior art; ' . FIGURE 2 - shows ore processing during the reducing calcination phase down to the pelletizing 10 known In the state of art;

FIGURE 3 - shows the schematic flowchart drying phase, pelletizing and screening of the crude pellets known ln the state of art;

FIGURE 4 - shows a Stralght-type fumace - Grade Induration Machine known to the state of the technique;

f

FIGURE 5 - shows a flowchart containing the mixture compound for pelletizing and the process ore route préparation, object of this Invention; '

FIGURE 6 - shows a Pot-Grate bumlng fumace’s schematic drawing used ln the simulated travelling g rate-type process.

FIGURE 7 - shows an Induction fumace used In the simulated 'steel beit process.

FIGURE 8 - shows a graph containing températures obtained during slntering tests ln the ' induction fumace according to FIGURE 7;

-, PHOTOS 1Â and 1B — show the commlnution equipment used ln the process, object of this Invention;

PHOTO 2 - shows à pelletizing disk used ln the simulated ‘travellng grate' process:

PHOTO 3 - shows crude pellets used ln the simulated travail ng grate process;

PHOTO 4 - shows the Pot-Grade bumlng fumace used In the simulated traveling grate process;’ _f

PHOTO 5 - shows a 400 mm diameter lab disk used in tha pelletizing test for the simulated steel beit' process;

PHOTOS 6A and 6B - show molsturized and dry pellets used ln the simulated steel belf process;

PHOTO 7 - shows 1300*C sintered pellets from the simulated ‘steel beit* process;

PHOTO 8 - shows a peltetizing disk used In the fabrication of crude pellets in the simulated grate klln process; and

PHOTO 9 - shows the buming fuma ce used In the simulated “grate klln process.

Detailed description of the Invention

Peltetizing is a mechanical and thermal agglomereting process to convert the ore’s ultrafine fraction into sphères of about 8 to 18 mm size with suitable characteristics for réduction fumaces feed.

The présent invention ailows for the production of pellets from manganèse ores without previous calcination and with a 40 to 60% passing size through a 0, 044 mm mash (coarser 10 material).

Manganèse ore pellel production based on this présent invention’s process compiles with lhe following phases:

) Manganèse ore drying;

2) Ore size préparation through comminution process;

3) Addition of fluxes (calcite or dolomite llmestone or other MgO sources such as serpentinlte, olivine, etc.) to manganèse ore;

4) Addition of agglomérant to the manganèse and flux ore misture;

5) Mixture of the resulting material from previous phase;

6) Final mixture pelletizing for the production of manganèse ore crude pellets;

7) Crude peilet screening;

8) Managanese ore peliet buming;

t

9) Bumt peilet screening; and

10) Stocking and shlpping of manganèse ore peilet.

This process applies to a more oxide manganèse ore as well as to ores from other 25 same-type metals with spécifie siza distribution, spécifie surface varying from 800 to 2000 cm²/g and percent smaller than 0.044 mm from 40 to 60%. The ore shall be prepared In such a way as to prevent the génération of ultrafine material.

As far as the ore préparation process is concerned, the selected equipment dépends on • the ore’s initial size. During this phase no bail milling shali be used for the materiafs particle size . 30 ' réduction. The most suitable equipment for the comminution process Is: crusher and relier press or only a roller press with or without recirculation. In the case of ore fraction greater than 0.5 or 1.0 mm mesh particles size shall be prevtously reduced so as to obtain 100% of the passing material through this mesh to be then submitted to the roller pressing process with and without

recirculation. Materials with a fraction smaller than 0.5 or 1.0 mm can be relier press processed with and without recirculation. There must be enough pressing until a spécifie surface ranging from 800 to 2000 cm’/g and/or a size from 40 to 60% Is attained for the 0.044 mm mesh passing material. In the case of finer size ore, that Is, those at the spécifie surface range and 5 with mesh 0.044 mm passing percent at the range or greater than 40%, crushing and pressing \ phases can be disregarded.

Crushing and/or relier press phases shall occur In a closed circuit with screen to ensure the desired product size from such operations.

The use of relier press with and without recirculation requlres previous ore drying, the 10 initial moisture of which is around 12 to 15% against final moisture between 9 and 10%. Drying shall be preferably performed In a solid or liquid fuel powered retary dryer aimed at power génération.

Following through the pelletizing process, after the manganèse ore size préparation, the comminuted material shall be mixed with flux, either calcite or dolomite limestone or any other 15 MgO source such as serpentinîte, divine, etc.

Flux dosage can vary from 0.1 to 2.0% by function of the desired chemical composition for the peliet Then the mixture reçoives the agglomérant dosage, which can be bentonite (from 0.5 to 2.0%), hydrate lime (2.0 to 3.0%) or CMC-type synthetic agglomérant, Carboximetiicelulose (from 0.05 to 0.10%). Quantités shall be suitable for the formation of 20 -, crude peilets with enough résistance to support the transportation up to the fumace and thermal shocks to which they shali be subject during drying, pre-bumlng and buming phases. Both moisturized and dry peilets résistance shall be at least 1.0 and 2.0 kg/pellet, respectively, with a minimal resiiience value, that is, 5 (five) drops.

Water dosage is performed during the peiletlzing phase, either by disk or drum. The 25 addition shall be by function of the mixture initial moisture In quantifies enough to allow for the formation of good physical quallty crude peliet Depending on the size and agilomerant addition, moisturecanvaryfrom14to18%.

Crude peilets shall be heat processed in a traveling grate*, grate kiln’ or a steel belttype fumace, depending mainly on the desired production volume. Due to thermal shock spécial 30 attention shall be given to peilefs both drying and pre-buming phases. The heating ratio shali vary from 50 to 150°C/minute. Maximum température and total buming time shall be such as to ensure final products quallty In terms of physical résistance, mainly compression résistance.

- Top maximum température can vary from 1280 to 1340°C and total time from 34 to 42 minutes.

Peilets compression résistance shall be et least 250 daN/pellet ' 35 In order to better explain the Invention examples of pelietizing and buming are given herelnafter but these should not be taken for limitative effects of the invention. The mixture

composition for pelletizing and the ore préparation route for ail examples are presented ln FIGURES. ,

The calclte limestone was added as a flux and CaO source for the formation and composition adjustment of slag ln the electrical fumace (FEA), and was prepared so as to hâve 70% of the material passing ln a 325 mesh.

Bentonite was added as agglomérant and flux for the pelletizing process. Managanese and SIO_a make a compound, the fusion point of which being on the order of 1.274°C.

PHOTOS 1A and 1B show commlnuflon equlpment used for the Invention: mill (A) and relier press, bench/pllot (B), used for the commlnution of ores and fluxes.

·, Exemple 1 - PelletizinQ and pilot scale manganèse ore buming -Travellnq Grate* Process

Raw matériels used ln the study were manganèse ore called MF15 from Mina do Azul (Carajâs/PA), Northen calclte limestone and bentonite from India. TABLE 4 shows the chemlcal analyses of the materials used:

Materials	Fs	Mn	sio,	ΑΙΛ	CaO	MgO	P	PPC
SFMn- MF15	4,74	44, 20	3, 72,	8,12	0,18	0.23	0,080	15,36
Calclte limestone	ND	0,020	2,15	0,89	51,93	1,25	0, 068	42,22
Bentonite Ashapura	ND	ND	83, 50	18,12	1,30	2,98	0,020	8,‘5O

TABELA 4 - Chemlcal analyses of raw materials

A speed-adjustable belt feeder, a 1 (one) meter diameter pelletizing disk, 45° angle, 19 rpm speed and a water spray-based dosage system were used during the crude pellet . production phase (PHOTO 2)

At times the disk angle was altered (from 45° to 43°) so as to allow for pellets to reach diameters ranglng from 10 to 20 mm by function of longer resïdence time. The purpose of this activity was to ensure that, following the buming phase, pellets would be kept within the range of 8 to 18 mm by function of ore contraction due to déhydration, which was observed In bench scale tests, during the buming and crude pellet calcination phases.

For the purpose of characterlzihg crude pellets as shown ln PHOTO 3, molsturized and dry crude pellets were subjected to compression résistance and number of drops assays (resillence), assays used to evaluate the performance of crude pellets while slmulatlng handllng phases during classification (crude pellet screening), haulage and transference to the buming fumace. The results are shown ln TABLE 5 as follows:

Résistance to compression (kg/p)	Number of drops
Molsturlzed	Dry
1,15	8. 49	90.73

TABLE 5 - Crude pellet phvslcal gualitv.

Following the production of crude pelleta, they were screened by 6,10,12.5,16,18, end 20 mm mesh for size distribution évaluation.

The 10-mm mesh passing materiais end the ones retalned on 20 mm mesh were discarded whiie materials within the range of 10 to 20 mm were mixed for the formation of crude pellet load to be heat processed in a Pet Grate-type pilot fumace.

FIGURE 6 and PHOTO 4 show a schematic drawlng where remissive figures stand for, respectlvely, (3) top: (4) mlddte; (5) bottom; (8) lining, and the figures indlcate (1 ) llning layer (10 cm) and (2) side layer (2 cm) and the peilet buming fumace photo. The following are data relative to such equipment

Pot-Grate buming fumace:

Internai diameter	30 cm
. Extemal diameter	'40 cm
Height	50 cm
Refractory iining .	plates of sllica-lumlnous material
Llning layer height	10 cm
Air pressure	variable
Air flow ‘	variable
Température range	0° Cto 1.350° C

For the assembly of the Pot Grate, bumt ore pelleta were used as llning layer, being protected by a grate/steel screen and for the side layer 6 mm porcelain sphères were used.

After being fed with crude pelleta, the fumace was sealed and the thermocouples were connected. The buming was scheduied during fumace load, spedfying the thermal profile to be executed so that crude pellets can go through upstream drying, downstream drying, preheating, heating, post-heatlng and cooling off without the génération of peilet degrading fractures. ·

Upon completion of the cooling phase, bumt peliets were thon unloaded, separated from the porceiain sphères, homogenlzed, quartered, and sent for compression and abrasion résistance physicai assays and chemical analysis.

Bumt pellets were then subjected to lab chemical analyses as shown In TABLE 6 as follows:

Mn	SiO]	CaO	Fe	AliOj	Comp. Resst	Abrasion Reslst.
41,00	5,92	2,43	5,71	9,25	250 daN/pellet	3,0 % <0,5mm Max

TABLE 6 - Bumt pelle! chemical composition.

The evaluated bumt pellet physical qualîty parameters were Résistance to Compression (RC), the resuit of which being 269 daN/pellet, and the Abrasion Index (Al), with 1.4% passing through a 0.5 mm mesh.

Norms and ISO (International Standardizatlon for Organizations) méthodologies for Iron ores were used to conduct the manganèse pellet quallty évaluation assays.

f

Exemple 2 - Pelletizing and bench scale manganèse ore buming - Sleel Belt* process

Manganèse ore fines chemical analyses were performed using mainly chemical to moisture methods, FAAS (atomic absorption), ICP (plasma), and a sulfur-carbon Leco analyzer. Heat loss wes measured in an atmosphère of N2 to 1100°C.

TABLE 7 shows the chemical analysis.

Compon ent	Mn	Fe	SIO î	CaO	Mg O	Al_aOj	K	Na	s	C	L.0 .I¹»	HjO
%	43.1	6.1	4.5	0.27	0.36	9.0	0.8 9	< 0.04	0.12	0.17	16. 5	8.2

) Heat loss

TABLE 7 - Mn ore chemical composition.

Caldte was used in tests as flux, the composition of which being as follows: heat loss of 49.6 % CaO and 43.0 %

The pelletizing test was performed In a 400 mm lab disk (PHOTO 5). The mixture for the pelletizing comprised manganèse ore fines, calclte and bentonite, which were Initlally manually mixed arid iately using a lab V mixer fpr 60 minutes. The mixed portion was manually fed into the disk. As the mixture wes fed into the disk water Is spray-controlled for the formation of pellets. The mean desired peilet diameter was 12 mm. Following the pelletizing test, moisturized and dry pellets diameters and compression résistance were then measured and the humldlty of moisturized pellets was calculated.

An induction fumace (FIGURE 7) was used for slntering tests. Pellets were transported In a 110 ml alumina crucible, which was placed Inslde a blgger graphite crucible, with the set being placed into an Induction fumace. The graphite crucible was previously lldded and air was Injected Into the test crucible with the System température being continuously measured. Pellets were then lab-scale heated in accordance with the desired température profile. The compression résistance target was 200 kg/pellet (suitable for a 12 mm size). FIGURE 6 shows these températures.

Pelletizlng tests results are shown In TABLE 8 and the photos of moisturized and dry pellets are shown In PHOTOS 6A and 6B.

Moisture (%)	Résistance (kg/pellet)
Moisturized	Dry
14,8 ·	1,46

TABLE 8 - Crude oellet phvslcal quality.

In the slntering test, pellets were heated pursuant to defined température profiles aîmed at a lab scale description of the slntering In the metalllc conveyor. Actual sintering conditions shall be researched by means of a pilot bench scale test during an upcoming phase. A targeted compression résistance of 200 kg/pellet (12 mm diameter petiot) was obtained at 1300°C. Compression résistance reached 300 kg/pellet at 1350°C. PHOTO 7 shows pictures of slntered pellets at 1300°C.

. Exemple 3 - Bench scale manganèse ores pelletlzirw and buming -‘Grate_Klln‘ process

Chemical compositions of both manganèse ore and Input used for Ihis study are shown In TABLES 9 Ihrough 11.

Elément	Fe_to(11	FeO	Fe₂O₃	Μη_Μ\|ι	MnO	MnOî	SIO2
%	6.49	1.87	7.21	42.73	1.52	65.75	5.79

Al₂o₃	CaO	MgO	K₂O	NajO	P	S	LOI
7.24 ·	1.12	0.26	1.19	0.042	0.093	0.035	6.82

TABLE 9-Manoanese ore chemical quality.

Elément	Feton	FeiOj	SIOj	AItOj	CaO	MgO	K2O	Na-O	P	S	LOI
%	9.10	13.01	50.97	17.32	2.89	0.28	0.16	2.52	0.053	0.03 5	11.9 1

TABLE 10 - Bentonlte chemical cualitv.

Elément	Fetow	Fe₂O₃	SiO₂	AI₂O₃	CaO	MgO	LOI
Grade	0.17	0.24	0.65	0.22	54.89	0.26	43.32

TABLE 11 - Calclte limestone chemical quatitv.

- Crude pellats made In pelletizlng disks (PHOTO 8) using manganèse ore mixtures.

limestone arid bentonite, as well as the effect of diverse parameters over the quality of crude ' 20 peilets were evaluated. The process parameters observed in this évaluation phase are as follows: .

- Pelletizlng conditions: pelletizlng time and compaction;

- Bentonlte dosage;

- Limestone size; _t

- Coal dosage.

TABLES 12 through 14 show the results of these évaluations:

(Juif

Pelletizing conditions	Bentonite/%	Number of drops	Moisturized compression résistance /N/pellst	Thermal shock Temp. K	Moisture /%
Pelletizing time /min ‘	Compaction Urne /min
' 12	2	1.5	59.9	13.74	540	15.72
12	0	1.5	51.1	10.01	520	15.60
7	• 2	1.5	9.7	9.50	449	16.61

TABLE 12 - Effects of pelletizing time and compaction and bentonite dosage over crude pellet gualitv.

Basicity/CaO/SIOî	Number of drops	Moisturized compression résistance , /N/pellet	Thermal shock Temp7°C
0.18 (natural basicity)	9.7	8.50	449
0.30.	10.8	13.48	270
0.50	9.1	14.03	261
0.70	13.6	16.39	260
0.80	13.8	12.14	225
. 1.10	19.6	14.85	206

TABELA13 — Basicity effects over crude pellet gualltv.

Coal addition %	Number of drops	Moisturized compression résistance /N/pellet	Thermal shock Temp^C
0	13.8	12.14	225
0.5	13.0	10.29	368
1.0	11.2 *	8.60	345

TABLE.14 - Effects of coal addition over crude pellet auallty. . .

Based on such results we can condude that:

- Most suitable pelletizing parameters should be the bentonite addition between 1.4 and 1.5%, moisture between 14 and 15% and pelletizing time on the order of 12 minutes. Under such conditions, drops totaled 50, and the thermal shock température was greater than 400°C while moisturized crude pellet compression résistance was greater than 10 10 N/pellet . '

- - Increased basicity Implied and Increased number of drops and Increased moisturized crude pellet résistance compression. A strlking decrease was also observed in the thermal shock température. On the other hand, the Increased addition of coal affeded sIgnificantly moisturized crude pellet compression résistance.

- Crude pellets were bumt In a vertical fumace (PHOTO 9) and during this phase the effects of the following parameters over bumt pellet résistance compression were eveluated:

- Pre-heating, time and température conditions;

- Heatlng, time and température conditions;

S - Binary basldty;

Coal addition.

TABLES 15 to 18 show the results o'f these évaluations:

Température (°C)	Time (min)	Compression résistance (N)
1	2
1010	8	492	542
1010	10	577	594
1010	12	544	551
1010	15	/	549

- Pelleüzing and rompection Urne of 12 and 2 min. respectively, and nomet heating r»tx>. • 2 * Pedettzlng and compacdon Orne of 7 end 2 min, respectively. and low heatlng rato. 3·% <0,044 mm· 00%.

TABLE 15 - Effects of température and pre-heating time over bumt pellet qualitv

Température ’ . (°C)	Time (min)	Compression résistance (N)
1	2	3
1250	15	/	1140	1232
1280	15	1493	/	/
1300	15 '	/	1437	1190
1316	15	1513	1881	2088 .
1330	15	/	/	/
1037 .	15	2433	2567	2241

- Pelletaing and compacdon lime of 12 and 2 mm, respecüvety. and low heating ratio.

- Pedstlzlng and compacdon lime of 7 and 2 min. respectively. and low heating rato.

- Pefletlzing and compacdon Urne of 7 min and low heatlng ratio.

- % < 0,044 mm 00%.

TABLE 16 - Effect of bumina température over bumt pellet qualitv

Température ' CC)	Time (min)	Compression résistance (N)
1	2
1337	12	/	1861
1337	15	2433	2567
1337	18	/	2530
1337	20	2338	/

- PeJeUdng and compacdon dme of 12 and 2 min, respectively, end low heedng raüo.

' 2 - PeUeüzIng and compaction time of 7 and 2 min. raepecBvaly, and low bottine ratio.

- % < Λ 044 mm - 60%.

TABLE 17 - Effect of bumlno time over bumt pellet aiialltv.

Température (°C)	Time (min)	Résistance to compression (N)
R0.3	R0.5	R0.7	R0.9	R1.1
1300	15	1120	1400	1438	1478	/
1320	15	’ /	1822	1853	2137	2235
1330	15	/	/	/	2167	2242 .
1337	15	2554	2799	2817	3138	3229
1337	12	/	/	/	/	2255

TABLE 18 - Effect of basicitv over bumt pellet aualltv

Coal(%)	Pre-heating température fc)	Pre-heating time (min)	Compression résistance (N)
0	1010	10	594
0.5	1000	10	241
0.5	1050	10	221
0.5	1100	10	260
1.0	1000	10	203
1.0	1050	10	178
' 1.0	1100	10	196

T

TABLE 19 - Effect of coal addition and pre-beatino time over bumt pellet quality.

Based on such results we can condude that:

(1) Crude pellet pre-heating conditions ara very important for the production of good quality preheated pellets. When crude pellets were produced with ore 60% smaller than 0.044 mm, 1.5% bentonite, pelletizlng time of 7 min and 2 min for compaction, température and pra10 heating time of 1010°C and 10 min, respectively, it was possible to produce pre-heated pellets with 600N compression résistance.

, (2) Bumt pellet compression résistance reached 600N during pre-heating and 2600N during • heating, where température and processing time were 1010°C and 10 min, during preheating, and 1337°C and 15 min during heating;

(3) Bumt pellet compression raslstance can be drastically improved with the addition of calcite limestone, with basicity varying between 0.3 to 1.1 during heating conditions mentioned In Item 2.

Claims

· . CLAIM S '· L PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE characterized by the fact that It comprises the following phases:

(a) ore size préparation through ore classification by function of particie size, smaller

5 or equal to 1 mm particles being malntained from lhe ore particie fraction process so as to hâve a smaller or equal to 1 mm size, as well as the commlnution of these particles;

(b) flux addition;

(c) agglomérant addition;

10 (d) pelletizlng resulting In crude pellets;

(e) thermal processing through drying, pre-heatlng and and heating the crude pellets.
2. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according to claim 1, characterized in that it can be appiied to any * more oxide manganèse ore and ores from other metals of the same type with spécifie

15 -, · size distribution.
3. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according to claim 1, characterized in that the ore drying phase occurs before the size préparation phase so as to ensure a maximum moisture of 9%.
4. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED

20 MANGANESE ORE, according to daim 1, characterized In that during the commlnution process at the size préparation phase both crushing and pressing operations are undertaken by function of ore particie size.
5. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according to claim 4, characterized In that at the ore size

25 préparation phase, a fraction of manganèse ore with particie size greater than or equal to 1.0 mm is handled with roller press.
6. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED • MANGANESE ORE, according to claim 1, characterized by the fact that at the end of the

-, - préparation process ore particles show spécifie surface between 800 to 2000 cm’/g.

30
7. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED

MANGANESE ORE, according to daim 1, characterized by the fact that at the end of the préparation process ore partides show size varying from 40 to 60% In terms of mass of the passing material through a 0,044 mm mesh.
8. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according to claim 1, characterized by the tact that the flux added during the flux addition phase Is caldte or dolomite Emestone, or their mixture, or any ’ other MgO sources.

5
9. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED

MANGANESE ORE, according to clalm 1, characterized by the fact that the agglomérant added during the agglomérant addition phase Is selected from the group comprising bentonlte, hydrated lime, carboximetilcelulose (CMC), or their mixture.
10. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED

10 MANGANESE ORE, according to daim 7, characterized by the fact that 0, 5% to 2% of mass is used, in relation to total bentonita mass. .
11. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according to daim 10, characterized by the fact that 2% to 3% of hydreted lime mass is used, In relation to total mass.

15
12. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according to daim 10, characterized by the fact that 0.05% to 0.10% of carboximetilcelulose mass Is used, ln relation to total mass.

’
13. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED

MANGANESE ORE, based on daim 1, characterized by the fact that at the end of the 20 pelletizing phase crude pellets with 1 and 2 kg/pellet minimal résistance, respectively, are formed, with a resillence of at least 5 drops.
14. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according )o daim 1, characterized by the fact that the crude pellet thermal processing phase occurs ln a traveilng grate, grate klln or steel belt-type

25 fumace.
15. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED MANGANESE ORE, according to clalm 14, characterized by the fact that the thermal processing phase shows maximum température varylng from 1280 to 1340°C.
16. PROCESS TO PRODUCE MANGANESE PELLETS FROM NON-CALCINATED

30 MANGANESE ORE, according to claim 14, characterized by the fact that the thermal processing phase total time ranges from 34 to 42 minutes.
17. IRON-MANGANESE AGGLOMERATE characterized by the fact that it Is obtained through the process redted by daims 1 to 16.
18. IRON-MANGANESE AGGLOMERATE, according to clalm 17, characterized by the fact

35 that comprises an average diameter between 8 and 18 mm.

• 19
19. IRON-MANGANESE AGGLOMERATE, according to daim 17, characterized by the fact that it shows a minimal compression résistance of 250 daN/pellet.

f

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