Minorca Mine
ArcelorMittal Profile

ArcelorMittal is the world’s number one 

steel company, with 310,000 employees 

in more than 60 countries. It has led the 

consolidation of the world steel industry 

and today ranks as the only truly global 

steelmaker.

ArcelorMittal is the leader in all major 

global markets, including automotive, 

construction, household appliances and 

packaging. The Group leads in Research 

and Development and technology, holds 

sizeable captive supplies of raw materials 

and operates extensive distribution 

networks. 

Its industrial presence in Europe, Asia, Africa 

and America gives the Group exposure to all 

the key steel markets. It enjoys a leadership 

position in technically advanced products. 

It benefits from a high level of vertical 

integration – from iron ore mining at one end 

of the value chain to steel service centers 

and distribution at the other.

ArcelorMittal’s strategy is to build a 

sustainable and stable business, creating 

value through the cycle, through scale 

and diversification. At the same time, 

the company is focused on setting the 

standard in areas such as health and safety, 

quality, delivery and customer satisfaction. 

ArcelorMittal remains engaged with the 

communities in which it operates and 

steadfast in its commitment to good 

environmental practice.

Core Values

Transforming tomorrow: Our Philosophy, Our Values

We know that our position in the steel industry brings unique responsibilities. We 

are committed to setting globally recognized standards with the needs of future 

generations in mind. 

Our goal is to provide the leadership that will transform tomorrow’s steel industry. We 

have a clear vision of the future, underpinned by a consistent set of values. 

Sustainability

We are guiding the evolution of steel to secure the best future for the industry and 

for generations to come. 

Our commitment to the world around us extends beyond the bottom line, to include 

the people in whom we invest, the communities we support and the world in which 

we operate. This long-term approach is central to our business philosophy. 

Quality

We look beyond today to envision the steel of tomorrow. 

Because quality outcomes depend on quality people, we seek to attract and nurture 

the best people to deliver superior solutions to our customers.

Leadership

We are visionary thinkers, creating opportunities every day. 

This entrepreneurial spirit brought us to the forefront of the steel industry. Now, we 

are moving beyond what the world expects of steel.

For more information, please visit www.arcelormittal.com

ArcelorMittal Minorca Mine | 2
Geology

Minnesota’s future as the iron-ore capital 

of North America was assured more than 2 

billion years ago. Then, a vast shallow sea 

covered much of what is now the Mesabi 

Iron Range. As time passed, material rich in 

iron and silica was deposited on the floor of 

this sea in thin, alternating layers. Because 

the water of this vast inland ocean was 

low in free-oxygen content, the material 

also was low in oxygen, helping to prevent 

decomposition. 

This period of geologic formation ended 

with the return of more common forms of 

sedimentation, such as mud, clay and sand. 

As the centuries passed, the weight and heat 

generated by this accumulation of material 

converted the iron and silica into taconite, a 

hard flinty rock containing about 22 percent 

magnetic iron. The eastern portion of the 

Mesabi Range, where Minorca is located, 

also benefited from the intrusion of hot, 

molten rock known as the Duluth Gabbro. 

At about the same time, the iron-rich rock 

strata was tilted between 3 degrees and 12 

degrees to the southeast.

The next stage of geologic formation 

occurred as the overlying rocks were 

slowly worn away, exposing the iron-rich 

strata to oxygen and water. These entered 

the formation along porous zones and 

fractures, reacting with the oxygen-poor 

minerals. As a result, the minerals oxidized 

to form hematite, or “red ore,” while the 

silica was washed away. The result was 

rich, red-ore bodies surrounded by oxidized 

(nonmagnetic) and unoxidized (magnetic) 

taconite.

Most of the red ore in the Mesabi Range was 

exhausted by the military buildup for World 

War II. New processes were developed to 

mine and extract the remaining iron-bearing 

material from the lower-grade taconite 

ore. As these sources of iron are depleted, 

technology may be developed to use the 

remaining nonmagnetic ore. 

Typical Laurentian Mine Cross Section

Steel is the fundamental raw material of the 

21st century, widely used in the manufacture 

of products for a variety of markets such as 

automotive, appliance, construction, office 

equipment, packaging and others.

ArcelorMittal USA is the largest steel 

manufacturer in North America. 

ArcelorMittal Minorca, near Virginia, Minn., 

is one of the company’s leading sources of 

iron ore – a major raw material required 

in the manufacture of steel. Each year, 

Minorca produces about 2.8 million tons 

of fluxed iron-bearing pellets, and mines 

about 18 million tons of ore, rock and waste 

material, called overburden. The pellets 

are then shipped to ArcelorMittal Indiana 

Harbor, North America’s largest integrated 

steelmaking complex located in East Chicago, 

Ind., about 20 minutes southeast of Chicago. 

There, the pellets are charged into Indiana 

Harbor’s massive No. 7 Blast Furnace – 

the largest iron producer in the Western 

Hemisphere, capable of producing more than 

12,500 tons of molten iron a day. Minorca 

supplies about 50 percent of No. 7 Blast 

Furnace’s pelletized iron requirements.

Blast hole survey.

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1600

1400

1200

1000

800

600

Burden

Lean Tac

UC-3 Ore

Waste Rock

LC-5B Ore

LC-5A Ore

LC-4 Ore

UC-2 Ore UC-1 Ore

ArcelorMittal Minorca Mine | 3
History

In 1780, nearly 150 years after the first 

French explorers visited northern Minnesota, 

the first recorded discovery of the iron-rich 

rock strata of the Lake Superior District 

was made on the Gunflint Range. Almost 

90 years later, in 1886, iron-bearing rock – 

although not ore in the commercial sense – 

was discovered at both ends of the Mesabi 

Range. Mineable ore was first discovered 

four years later, in 1890, about five miles 

west of what is now Minorca Mine. 

This discovery triggered rapid exploration 

and development of red ore mining 

capability. By 1900, the main outline of the 

Mesabi Iron Range was basically defined. As 

the richest portions of these direct shipping 

red ore deposits were exhausted, tons of 

leaner mixtures were encountered. This ore 

could be upgraded by simple washing and 

screening techniques. These methods were 

first employed on a large scale in 1910. 

As reserves of natural high-grade ores 

diminished, mining operations increasingly 

turned to such procedures until nearly all 

of the remaining red ores were mined and 

upgraded. 

Early on, it was recognized that the hard, 

lean, dark-colored rock that surrounded 

the brightly colored red-ore bodies was 

highly magnetic. It also was discovered that 

the eastern 20 miles or so of the Mesabi 

Iron Range was composed of this same 

hard, flinty rock, called magnetic taconite. 

The first effort to upgrade these ores on 

a commercial scale was made in 1918. 

However, due to the high cost of mining, 

crushing and grinding the extremely hard 

rock, this small-scale operation ceased in 

1924. The modern age of magnetic taconite 

mining and processing had to await the 

development of new techniques, such as 

jet-piercing and pelletizing, before it could 

resume in the early 1950s.

Minorca Mine Development

Shortly after World War II, Inland Steel Co. 

acquired half ownership of the Pacific Isle 

Mining Co., which held natural-ore mining 

leases on property encompassing the 

Minorca Mine. The company purchased the 

remaining interest in Pacific Isle in 1960, 

and began exploratory drilling for taconite in 

1962. The natural-ore leases held by Pacific 

Isle were amended to include taconite, and 

additional mining properties were leased. 

Land on which to build the plant and auxiliary 

facilities was acquired from the U.S. Forest 

Service, state, county, and other corporate 

and private land owners. 

A study then was made to determine if 

sufficient water was available for operation 

of a taconite plant. In 1973, preliminary 

engineering and cost/benefit studies were 

made. Based on the results of these studies, 

the company’s board of directors authorized 

the development of the Minorca Mine 

Taconite Project in 1974. The first shipment 

of taconite pellets was made in June 1977. 

Minorca Mine was originally owned by Inland 

Steel Mining Co., which was formed in 1974 

as a wholly-owned subsidiary of Inland Steel 

Co., an operating subsidiary of Chicago-based 

Inland Steel Industries Inc.

In 1993, the company opened up a new ore 

body called the Laurentian 

Mine near Gilbert, Minn., 

about six miles from its 

production facilities. 

In 1998, Inland Steel and Minorca Mine 

were purchased by Ispat International and 

renamed Ispat Inland Inc. In 2006, the 

company became Mittal Steel. Finally in 

2007, the merger between Mittal Steel with 

Arcelor formed the largest steel company 

in the world – ArcelorMittal. The Minorca 

operation was then renamed ArcelorMittal 

Minorca.

In 2007, ArcelorMittal began mining the 

East Reserve between McKinley and Biwabik, 

Minn.

ArcelorMittal Minorca Mine | 4
Minorca Mine Operation Overview

1. Taconite ore is drilled, blasted and trucked 

to the plant. Overburden and rock are 

trucked to stockpiles.

2. Taconite is crushed to football-sized 

chunks in the primary crusher.

3. Ore is moved by conveyor to an 

intermediate stockpile.

4. Ore is crushed to gravel-size during 

second-and-third-stage crushing.

5. Ore is moved by conveyor to the fine ore 

stockpile.

6. Ore is ground to face-powder size in rod 

and ball mills. Iron-bearing particles are 

separated from the ore magnetically and 

chemically. Finely-ground fluxstone is 

mixed with the concentrate. 

7. Fine tailings are partially dewatered in 

the tailings thickener and pumped to 

an enclosed basin. Coarse tailings are 

trucked to a stockpile.

8. Fluxstone (55 percent dolomite and 45 

percent limestone) is crushed and ground 

in the fluxstone grinding plant.

9. A clay binding agent is added to the 

taconite concentrate and rolled into 

marble-sized pellets.

10. Pellets are heat-hardened at 2,450o F 

in a gas-fired furnace.

11. Finished pellets are stockpiled prior to 

train shipment to Two Harbors, Minn.; 

then moved by boat to Indiana Harbor, 

East Chicago, Ind.

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ArcelorMittal Minorca Mine | 5
Fluxed pellets from Minorca Mine travel three 

days across the Great Lakes, where they are 

stockpiled at ArcelorMittal Indiana Harbor.

Photo: Mr. François Trahan, 2006

Iron ore pellets and other raw materials 

are used in blast furnaces, such as 

ArcelorMittal Indiana Harbor’s No. 7 

Furnace, to produce liquid iron.

BALL MILL

BIN

TAILS

TANK

SCREEN HL

HL1,2

HL3,4

RECLAIM

GRIZZLY

HL

OU2,3

FEEDER

STAMLER

FCR1

BIN

HL MD-2 BIN SPLITTER

CRUDE ORE

SCREEN

CRUSHER

TERTIARY CRUSHER

SECONDARY 

52CV02,3,4,5,6,7,8,9

51CV09,52CV01

44CV01

43CV01

C-3

FINE SCREEN

TANK

STORAGE

SLURRY

FLUXSTONE BALL MILL

CRUSHER

BIN

FLUX FLUXSTONE UNLOADING

SUMP

FMS 

FLOT 

PLANT

TANK

SLURY

CONCFLUXED

TANK

SLURRY

CONCACID

THICKENER

CONCENTRATE FINISHERS

FINE 

SCREENS

HYDRO-SEPARATOR DESLIMING

CYCLONE

TO TAILINGS BASIN

TAILS THICKENER

ROUGHER

SPIRAL CLASSIFIER

62CV-01

FC 1,2,3,4,5,6,7 FCS-1

FILTERS

BALLING DISC

BIN STORAGE

CAKE

FILTER BIN BENTONITE BIN

PERIDUR

REPULPER

GP 1,2,3,4

MACHINE

INDURATING

PELLET LOAD-OUT

P-1,P-2

MD-1

MD-2 STOCKPILE P-3

COBBER

ROD MILL

PRIMARY CRUSHER

PELLET STOCKPILE

FILTER CAKE STOCKPILE

BLENDING PILE

FINE ORE SURGE PILE

COARSE

ArcelorMittal Minorca Mine | 6
Drilling and Blasting

A 16-inch rotary drill makes 

between 100 and 200 holes for 

each blast site in a grid 26 feet 

by 30 feet. Each hole is drilled 

into the rock strata to a depth of 

35-50 feet. Next, about 3,000 

pounds of ANFO, an explosive 

mixture of ammonium nitrate and 

fuel oil, is bulk loaded into each 

hole and covered with a 16-

foot plug of crushed rock called 

“stemming.” 

Each blast carries the explosive 

force of more than 250,000 

pounds of dynamite and 

dislodges between 200,000 

and 300,000 tons of rock. The 

blast is triggered sequentially 

using 25-millisecond, nonelectric 

delay units between each hole, 

sending an explosive shock wave 

through the rock that fragments 

the taconite into pieces ranging in 

sizes from just inches to boulders 

several feet in diameter. Rock 

type and hardness determine the 

blast design, but about one pound 

of explosive is needed to break 

each ton of taconite ore. The 

broken crude ore, which contains 

about 22 percent magnetic iron, 

is excavated by giant loaders 

equipped with 19-cubic-yard 

buckets and then dumped into 

195-ton or 240-ton haul trucks, 

and delivered to the plant for 

processing.

Stripping

Before iron can begin its journey to liquid 

steel, it must be mined as ore from the 

ground. To begin, earth and waste rock 

covering the ore must be removed and 

placed in stockpiles. For every ton of ore 

mined, about one ton of overburden and 

waste rock must be removed. 

ArcelorMittal Minorca Mine | 7
Fine Crushing

A conveyor beneath the coarse 

ore stockpile moves the ore to 

the fine crushing plant, where it 

is reduced to less than 5/8 inch in 

second-and-third-stage crushers. 

Ore crushed to the desired size is 

continuously moved by conveyor 

to the fine ore stockpile. A 

traveling conveyor deposits ore 

on the pile and ensures the ore is 

blended for increased quality and 

uniform plant feedstock.

Rod Mills

Conveyors beneath the fire ore stockpile 

move the ore to the concentrator building, 

where it enters one of three identical 

processing lines. First, the ore is fed by 

conveyor into rod mills, where it is mixed 

with water to form a slurry, for ease of 

transport through the remainder of the 

grinding process. Inside the rod mill, 200 

tons of hardened steel grinding rods, each 

19.5 feet long, four inches in diameter and 

weighing 800 pounds, tumble over the 

slurry, reducing the size of the ore particles 

to about the consistency of sand.

Coarse Crushing

The 54-inch diameter primary crusher 

reduces boulder-sized pieces of taconite 

to about the size of a football. As crude ore 

is dumped into the top, gravity pulls the 

rocks downward, where the crusher breaks 

them into even smaller pieces, operating 

like a huge inverted mortar with a circular 

motion pestle. A conveyor belt moves ore 

from beneath the crusher to a 70,000-ton 

coarse ore stockpile. The process takes 

about five minutes. 

ArcelorMittal Minorca Mine | 8
Magnetic Separation

Ore discharged from the rod mill is fed into 

rotating magnetic separator drums called 

cobbers, which extract the iron-bearing material 

from the surrounding silica and rock. This waste 

silica and rock, called tailings, flows by gravity 

to a classifier that separates the tailings by 

size. Coarse tailings are trucked to stockpiles 

where they later will be used for roads or other 

construction applications. Fine tailings are sent 

to a tailings thickener for partial dewatering 

and then pumped to a reservoir called a tailings 

basin, where tailings are allowed to settle to the 

bottom and the clarified water is pumped back 

to the plant. 

Ball Mills

Following magnetic separation, the ore moves to the ball mills 

where 350 tons of rotating steel balls, each 1.5 inches in diameter, 

reduces the ore to about the consistency of face powder. The ore is 

then passed through a second series of magnetic separators called 

roughers. The rougher concentrate is size-classified by cyclone 

separators. The cyclone overflow moves to hydroseparators, where 

the ultra-fine material is rinsed out of the concentrate. Concentrate 

from the hydroseparators is then pumped to vibrating screens, which 

again size-classify the material to ensure the correct particle size and 

consistency. The oversize from these screens is fed back into the ball 

mill for further reduction. The undersized material is fed to the final 

series of magnetic separators called finishers. 

Flotation Separation

The slurry concentrate moves to the final stage of processing: 

flotation separation. Through the use of chemicals, air and 

mechanical agitation, bubbles are formed in each of eight 

1,000-cubic-foot flotation cells. The fine particles of silica 

attach to the bubbles and are removed from the concentration 

process. Flotation concentrate is pumped back to the concentrate 

thickeners and the silica from the cells is subjected to additional 

grinding and flotation. This recovers iron trapped in the froth, 

which otherwise might be lost in the process. 

Thickeners

The flotation concentrate is fed to two concentrate thickeners 

where partial dewatering of the concentrate occurs. At each stage 

of the concentration process, waste material is pumped to a tailings 

thickener and partially dewatered. Water from the process – about 

70,000 gallons a 

minute – is cleaned 

and returned to 

the manufacturing 

process. Tailings 

are pumped to an 

enclosed basin, 

where they settle 

to the bottom, and 

the clarified water is 

pumped back to the 

plant and reused. 

ArcelorMittal Minorca Mine | 9
Flux Grinding Plant

In 1987, Minorca Mine introduced the first 

fluxed pellet on the Mesabi Iron Range. 

Fluxed pellets improve blast furnace 

productivity, make higher-quality iron, 

and reduce energy and maintenance costs. 

Limestone and dolomite, called fluxstone, 

arrive at Minorca in railroad cars. The 

fluxstone is then crushed in a slurry much 

like taconite and ground to about the 

consistency of face powder in the flux 

grinding plant. The finely-ground slurry 

is then pumped into a 40-foot diameter 

slurry holding tank in the concentrator 

building, where it is mixed with the iron-rich 

concentrate at a specified rate and ratio.

Disc Filters

Indurating Furnace

The fluxed taconite concentrate now 

undergoes dewatering through a series 

of disc filters. Water is removed from the 

concentrate by vacuum on a series of clothcovered discs. What remains on the disc is 

filter cake containing about 9 percent water 

and more than 62 percent magnetic iron.

The green, unfired pellets are conveyed to 

a 13-foot-wide traveling grate to begin 

their 250-foot trip through the indurating 

furnace. Inside, the balls are dried and 

heat-hardened at 2,450o F in six, carefullycontrolled heating and cooling zones. 

Balling Discs

The dewatered filter cake is mixed with 

bentonite clay, a kind of glue that will hold 

the pellet together through the baking 

process. The mixture is then rolled into 

marble-sized balls on rotating 19-foot 

diameter discs.

COOLING AIR FAN

DRYING ZONE

PREHEAT BURNERS

UPDRAFT

UPDRAFT DRYING FAN

HOOD EXHAUST FAN

FIRING ZONE FIRING

WINDBOX

RECOUP FAN

WINDBOX

EXHAUST FAN

DRYING ZONE

DOWNDRAFT

ZONE COOLING

COMBUSTION CHAMBERS

AFTER

SECOND

COOLING

ArcelorMittal Minorca Mine | 10
Shipment

The finished pellets are transferred to a 

loading pocket for shipment 75 miles to 

Two Harbors aboard 116-car unit trains. 

At Two Harbors, the pellets are loaded 

into Great Lakes ore freighters (the size of 

three football fields), which carry them to 

ArcelorMittal Indiana Harbor, more than 

450 miles away. The three-day journey 

takes the pellets across Lake Superior, 

through the Soo Locks, down the St. 

Mary’s River, into Lake Huron, through 

the straits of Mackinac and into Lake 

Michigan.

Process Control

All process equipment is monitored from 

a central, computerized control room. In 

2007, a Distributed Control System (DCS) 

was installed to monitor stack emissions 

throughout the processing plant. It is also 

being used to record plant operating data 

in real-time and serves as a helpful tool in 

optimizing plant performance.

Reclamation

New pit slopes and filled tailings cells are 

planted with native grasses and trees each 

year to prevent soil erosion and control 

fugitive dust.

Quality Control

Technicians at Minorca constantly 

monitor, test and analyze ore 

samples to ensure the highestquality fluxed pellets. 

An X-Ray Fluorescent Unit is used to measure 

pellet quality.

ArcelorMittal Minorca Mine | 11
ArcelorMittal Minorca

Iron Mining

5950 Old U.S. Highway 53

Virginia, MN 55792

USA

T +1 218 749 5910

www.arcelormittal.com