INTRODUCTION
The present invention relates to manufacture of fused dolomite from raw or
calcined dolomite of Himalayan origin including Bhutan and Indian region and
articles made therefrom. More particularly this invention pertains to a
process for the manufacture of fused dolomite by electro fusion of raw
dolomite, preferably of Himalayan origin, accessed from Bhutan and
Himalayan foothills in India or of light calcined dolomite, and shaped articles
made therefrom. The desirable characteristics are imparted to the end
products, namely, fused dolomite, on account of formation of sub-hedral to
anhedral shaped Periclase crystal.
Presently dolomite bricks are widely used in refining furnaces for stainless
steel production in AOD/ladle. These bricks are mostly made from dolomite
clinkers. Dolomite clinkers are made by sintering raw dolomite in shaft or in
rotary kiln at a temperature of around 1800°C - 1900°C. It is also called as
"doloma" or sintered magnesia dolomite. "Mag-dolo" clinker is also obtained
by sintering pellets made from calcined 'dolo' and calcined magnesia in shaft
kiln or rotary kiln at about 1800 °C - 1900 °C. Bricks made with doloma are
used mostly on non-critical areas like metal zone and above slag zone while
bricks made from doloma along with magnesia are employed in critical area
like tuyere surrounding and slag zone of AOD converter.
PRIOR ART
(1)US Patent No. 3,940,279 narrates the use of dolomite, dead-burned
dolomite (a mixture of periclase and calcia) or fused dolomite (a solidified
melt of dolomite or equivalent calcia and magnesia) with or without excess
magnesia for making refractory. The biggest problem is hydration of the
dolomite or dead-burned dolomite grains to form calcium hydroxide with
an incident volume expansion and weakening of the body.
Fused dolomite grains have attracted attention because of their increased
hydration resistance but they still suffer somewhat from hydration.

Accounts of fused dolomite refractory and grain can be found in US Pat.
Nos. 3,540,899 and 3,262,795. Both suggest improvements relating to the
art of fusion casting of basic refractories.
A refractory made of fused or dead-burned dolomite grain (coarse and
intermediate fractions) bonded with fine magnesite (in fine fraction) has
been discussed. Size fractions are separated by large discrete gaps in the
size distribution of particles resulting in a burned refractory of high hot
strength and corrosion resistance to slags in basic oxygen furnaces.
(2) US Patent No. 3,262,795 for Basic fused refractories:
Earlier basic refractories for use in the oxygen converter were made of
the basic refractory materials like magnesia, dolomite, and calcia. But they
suffer from disadvantages because of their susceptibility to pronounced
hydration. Many workers have suggested stabilization of these materials
against attack by moisture. Iron oxide has been-widely used as a
stabilizing additive; for instance, of the order of 5 to 8% by weight. Such
iron oxide addition has suppressed the tendency of lime and dolomite to
hydrate; but the reaction of lime or calcia and iron oxide results in the
formation of dicalcium ferrite (2CaO.FeO) which melts at a relatively low
temperature of 2650 °F, compared to the melting point of pure lime of
about 4765 °F. Calcined lime and dolomite, in the absence of stabilizing
agents, however, do not have the high density and concomitantly low
porosity desired for refractory use. Iron oxide advantageously improves
density, but its presence has serious adverse effects affecting
refractoriness.
Suitable raw material for the fusion is selected from the group consisting
essentially of crude or burned dolomite, compounds of lime and magnesia,
including mixtures thereof, which material satisfies the critical chemistry,
as required. Suitable material is manufactured according to the process of
the United States Patent to Snyder et al, No. 3,060,000, or the Patent to
Leatham et al. No. 3,060,042.

Fusions were made for test purposes in a conventional electric arc melting
furnace. The fusion had magnesia to calcia weight ratios of about 70/30,
80/20 and 92/8.
The fusion is further characterized by a macro-crystalline structure, in
which relatively large abutting crystals are directly bonded to each other
with any spinel, aluminates, ferrites, etc., or silicate present as isolated
pockets within single crystals and as discontinuous films between the
crystals.
(3) US Patent No. 3,540,899 relating to Basic fused refractory material:
This deals with fusion of dolomite by adding sintering materials like
calcium fluoride, chrome, Fe2O3 etc. These additives densify the fused
grain.
Fused refractory material consisting of, analytically by weight, 38 to 85%
CaO, 10 to 59% MgO, at least 80% CaO plus MgO, 0.15 to 11.5 fluorine, to
10% oxide selected from CrO and/or FeO up to less than 7% SiO and O up
to less than 10% fluorine provides increased hydration resistance and, in
presence of CrO and/or FeO increased resistance to thermal shock and to
thermal gradient stresses. At least 0.5% by weight of CrO and/or FeO
yields higher bulk density.
(4) US Patent No. 3,901,721 for DOLOMITE-MAGNESITE REFRACTORY AND
BATCH THEREFOR:
Rebonded basic refractory consists of 65 - 75% (-4+65) mesh coarse
grain bonded with - 100 mesh (preferably at least 65% thereof being -325
mesh) magnesite fines. The coarse fraction in the batch is a mechanical
mixture of (based on the whole batch) 10 - 55% dead burned magnesite
and 15 - 60% fused dolomite (or equivalent mixed oxides).

The batch consisting of the coarse fused grain is composed of a melted
and resolidified raw material selected from dolomite, calcined dolomite and
dead burnt dolomite which should have at least 98% CaO plus MgO.
Other claims are based on size fractions with different % of CaO and MgO.
Refractory body is burned at 1600 °C.
(5)US Patent No. 3,540,89013,058,834 for PROCESS OF MAKING BASIC
REFRACTORY AND BASIC REFRACTORY COMPOSITION:
This Patent teaches first to calcine the dolo at low temperature and then
to be mixed with alumina to prepare bricks at 1800 °C, but nowhere it
mentions use of 100% fused dolomite for making refractory bricks.
(6) US Patent No. 3,930,874 for BONDED FUSED GRAIN BASIC REFRACTORY
AND BATCH THEREFOR:
Size graded batch for the production of basic refractory bodies and
consisting essentially of, with percentages on the weight basis, a mixture
of:
(a) dead-burned magnesite,
(b) at least one strength additive selected from the group consisting of
materials yielding Silica, Zirconia, and mixtures thereof, and
(c) at least one refractory grain analytically consisting essentially of 50 -
67% MgO and 33-50% CaO and selected from the group consisting of
dead-burned grain, fused grain, and mixtures thereof, 40 - 50% of the
batch being a coarse grain fraction whose grains are substantially all -
4+35 Tyler mesh and composed of said refractory grain, 20 - 30% being
an intermediate grain fraction whose grains are substantially all -20+65
Tyler mesh.

BACKGROUND OF INVENTION
Prior art discussed above mostly deals with dolomite refractory. Manufacture
of dolomite bricks made from sintered/fused dolomite with additive to
suppress hydration, mixed with fused/dead burnt magnesite in different
proportions having different size fractions for better compaction have been
disclosed in the aforementioned prior US Patents, which also deal with firing
of refractory bodies at about 1800 °C.
However, none of the prior Patents mention about the manufacture of
dolomite refractory by use of 100% fused dolomite. .Said prior Patents deal
with combination of magnesite and sintering additives, such as, for instance,
chrome based iron oxide addition, fluoride addition, and so on.
On the other hand, the subject invention relates to electro fusion of
raw/calcined dolomite of Himalayan origin, accessed from Bhutan and
Himalayan foothills in India. Dolomite is selected from this region because of
its availability in highly pure form, rendering it eminently suited for making
fused dolomite refractories extensively used in iron and steel industries as
well as in other non-ferrous industries.
THEORETICAL CONSIDERATIONS
For making fused dolomite, refractory grade raw dolomite with very low
impurity is preferred. Raw dolomite occurring in nature contains
CaCO3.MgCO3, with impurities like A12O3, Fe2O3, SiO2 and refractory grade
dolomite is characterised by that with less than 3% of such impurity(s).
Fused dolomite or Mag-dolomite is similarly made by fusing raw dolomite or
mixture of calcined dolomite and calcined magnesite in an electric arc furnace
at about 2700 °C. The average periclase crystal size of fused dolomite or
fused mag-dolo is >40 micron compared to <15 micron in case of sintered
dolomite. Density of fused dolomite is >3.30g/cc in comparison to that of
sintered dolomite <3.25g/cc. Low impurities like Al2O3 protects fused
dolomite from corrosion to steel slag in steel furnace. High impurity in

dolomite otherwise could form low melting compounds like calcium
magnesium silicates (CMS and C3MS2), calcium iron ferritc (C4AF), etc. which
corrode easily in stainless steel plant operation. Moreover, during fusion
process the impurities move towards periphery of the lump with more pure
material migrating towards centre. All these properties render fused dolomite
made from raw dolomite superior to that of sintered dolomite.
The principal object of the present invention is to provide a process for the
manufacture of fused dolomite from raw or calcined dolomite and articles
made therefrom.
A further object of this invention is to prepare refractory bricks and shapes
made from the fused dolomite produced by electro fusion of raw or calcined
dolomite in accordance with the subject process.
A still further object of this invention is to manufacture fused dolomite by
electro fusion of raw dolomite, preferably of Himalayan origin, accessed from
Bhutan and Himalayan foothills in India.
Another object of this invention is to provide a process for electro fusion of
raw/light calcined dolomite to produce 100% fused dolomite.
Yet another object of this invention is to provide a process for producing
fused dolomite refractories which not only increases the life span of steel-
making furnaces and vessels, but also ensures prevention of corrosion with
attended cost effectiveness.
The foregoing objects of this invention are achieved by a process for the
manufacture of fused dolomite by electro fusion of raw or calcined dolomite
and articles made therefrom, characterized in that the raw material selected
for the process is of the following composition:
(i) CaO - from 20 to 70% by weight
(ii) MgO - from 15 to 50% by weight

(iii) SiO2 - from 0.1 to 10% by weight
(iv) Fe2O3 - from 0.1 to 5% by weight
(v) Al2O3 " from 0.2 to 3% by weight
(vi) Fluorine - less than 0.2% by weight
(vii) LOl (loss on ignition) - from 40 to 50% by weight
which is subjected to calcination, if and when needed, at a temperature of
1000 °C and raw dolomite or calcined mass is partially filled in the base of the
empty fusion pots followed by coke breeze and/or carbon pieces, then a
plurality of electrodes are introduced in the partially filled fusion pot, which in
turn are connected by cable(s) to 1600 KVA transformer and equipped with
mechanical or hydraulic lifting devices and a number of cycles of current is
passed through the charge, wherein from second cycle onwards, semi-fused
dolomite is fed first into the fusion pot and then raw dolomite, preferably of
25 - 40 mm size, is added at a required rate through a vibro feeder, after the
culmination of the fusion process electrodes are lifted, the fusion pot with its
contents are cooled till reaching ambient temperature, the fused contents arc
taken out by being released on an inclined floor where under-fused and
semi-fused materials are sorted out and recycled and fused dolomite mass is
crushed and stored by packing in moisture-proof bags, and the stored
product may be marie into refractory bricks and shapes with the help of a
suitable binder, followed by compaction, firing and storage.
The subject invention also relates to a process as defined above, wherein
empty fusion pots are kept on a trolley car under the furnace station with the
help of a transfer trolley, fusion pot base is filled with raw/calcined dolomite
up to a height of around 0.5 m, after electro fusion the pot with fused material
is taken out by Winch system to keep the trolley car on the back line for slow
cooling for over 48 hours, thereafter the pot with its contents is taken out by
overhead crane followed by further cooling of the base for over 48 hours and

then the cold fused material on the base is lifted on a 10-degree inclined
floor, the fused dolomite ingots are broken to pieces either mechanically or
manually, fused, semi-fused and under-fused dolomite .are sorted out and
stacked separately, fused dolomite lumps are crushed in a jaw crusher/rolled
crusher to desired size fraction and fused dolomite pieces are packed in
moisture-proof bags, wherein grain bulk density of fused dolomite has a
minimum value of 2.98gm/cc.
The preferred composition of raw dolomite utilized as the starting material in
the abovementioncd process may be enumerated as follows:
(i) crushing fused dolomite lumps to size fraction varying between 6 mm
and 200 mesh;
(ii) mixing fused grains with binder in hot condition in a counter current
mixer/intensive mixer;
(iii) compacting the mix in a mechanical/hydraulic press to achieve desired
compaction density;
(iv) firing the refractory body at a temperature exceeding 1500 °C to attain
desired fired properties:
(v) subjecting the bricks/shapes to an anti-hydration treatment to protect
them from hydration and rendering them suitable for long storage and
(vi) packing the products in suitable containers, preferably under vacuum.
Analysis of Himalayan and Bhutan raw dolomite is shown in Table - 1 given
below:


The present invention will now be further defined by the illustrative drawings
accompanying this specification wherein—
Fig. 1 exhibits a flow chart diagram of the process for producing the
desired products by fusion of raw dolomite.
Fig. 2 depicts microstructure of fused dolomite bricks, and
Fig. 3 shows microstructure of fused dolomite bricks after use in steel
units.
From the flow sheet diagram of the electro fusion process for producing
fused dolomite, it will be evident that the process has an in-built step of
recycling unfused and/or semi-fused dolomite, which not only ensures
substantial utilisation of the raw material and its unconverted or semi-
converted forms, but also renders the process extremely cost effective, not
to speak of minimum amount of solid wastes.
With regard to Fig. 2 of the drawings, the respective markings signify the
following:
2A - shows Periclase surrounded by lime:
2B - 1 shows calcium ferrite found in inter-granular space;
2B - 2 shows Periclase phase;

2C - 1 shows lime phase in matrix and
2D - shows lime in matrix surrounding Periclase.
Referring to Fig. 3 of the drawings illustrating microstructure of fused
dolomite bricks after use in steel-making units, the following significance can
be ascribed to the respective connotations:
3A
each shows hot face with steel and slag infiltration;
3B
3B - 1 shows hot face with steel;
3D - shows cold face having no infiltration, and
3D - 1 shows Periclase surrounded by lime.
The invention will be further amplified by the following Example which is
given by way of illustration and not by way of limitation.
Example
(i) Fusion Process
Stud type (fixed) or pot type electric arc furnace is used for batch
production of fused dolomite. It consists of transformer, graphite
electrodes, transferable cylindrical shaped steel shell, and dust catcher
system.
Shell bottom is filled to about 550 mm initially with raw dolomite on
which a layer of coke breeze and 80 - 100 mm carbon pieces are put
on. Then a plurality of electrodes is lowered optimally 3 in numbers.
Power is put on to generate arcing and fusion process starts with
fumes and flames. After 20 minutes, about \ T of material size fraction
(20 - 45) mm raw dolomite/calcined dolomite/semi-fused dolomite
alone or in combination is added in intervals followed by another IT of

material in next 10 minutes. During initial 2 hours addition is done at an
interval of 30 minutes. Fusion starts from top of the filled material.
Addition of material is done in the vicinity of 3 electrodes from two
sides. Filling and fusion goes on in batches as each addition is followed
after fusion of previous material. Electrodes are raised after completion
of fusion and then lowered after filling of the material at each stage.
The feeding and arcing time depends upon the furnace size, quantity
and nature of feed material. The dust and fumes generated during
operation are collected in a dust catcher system, attached to the
furnace top hood. The shell with fused liquid mass is cooled down into
a bulk mass by natural/forced cooling. Then the shell is pulled out
mechanically from top and the fused lump is further cooled, followed by
breaking, sorting and crushing, depending on degree of fusion.
(ii) Electricity input particulars
Transformer rated capacity - 1.8 MVA
Primary voltage - 10 KV
Secondary voltage - 108 - 140 Volts
Dolo fusion done at - 128 Volts
Normal power consumption is about 1600 - 1700 units/hour
(iii) Detailed fusion process
• Shifting of empty fusion pots (base + pot of 1.7m dia and 3.4m
height) kept on a trolley car under the furnace station by transfer
trolley.
• Filling of pot base (0.5m height) with sized raw dolomite (20 - 45
mm), then with coke breeze and carbon pieces.

• Placement of 3 electrodes (connected to the cable 1600 KVA
transformer and with mechanical/hydraulic lifting devices) into the
partially filled fusion pot.
• From 2nd cycle onwards, semi-fused dolomite is fed first into the pot
and then raw dolomite (25 - 40 mm) at the required rate through a
vibro-feeder.
• Once the fusion process is over, electrodes are lifted.
• Loss of raw dolomite is about 50% in the fusion process (CO2 +
dust).
• The pot with fused material is taken out by Winch system to keep
the trolley car on the BG track line for natural cooling for 48 hours.
• After natural cooling, the pot is taken out by pulling with the help of
overhead crane.
• The fused material on the base is allowed to cool down further for
48 hours.
• Tilting of the cold fused material on the base by overhead crane on,
a 10 degree inclined floor.
• The base with trolley car is shifted by overhead crane from the
unloading area and kept on the BG track line for further use.
• After 12 hours of fusion cycle, the transformer needs cooling for
further 3-4 hours before it is put into operation for next fusion
cycle.
(iv) Processing of fused and semi-fused dolomite
• The fused dolomite ingots are broken into pieces
manually/mechanically.

• Fused, semi-fused and under-fused dolomite pieces are sorted
manually and stacked separately.
• Fused dolomite lumps are crushed by jaw crusher/rolled crusher to
desired size fraction.
• Fused dolomite pieces are packed in moisture-proof bags.
MANUFACTURE OF REFRACTORY BY USE OF 100%" FUSED DOLOMITE
GRAINS
Production of fused dolomite bricks with 100% fused dolomite grains are
carried out as follows:
Crushing of fused dolomite:
Crushing of fused dolomite lumps to size fraction from 6 mm to 200 mesh
are made by crushing and grinding with the help of various machineries
and equipment. Batch is made by weighing various fractions to get
optimum filling density. Mixing of fused grains with binder is made in hot
condition in a counter current mixer / intensive mixer. Soon after mixing
compaction is made in a mechanical/hydraulic press to achieve desired
compaction density.
Then the refractory has to be fired at a temperature exceeding 1500°C to
achieve desired fired properties. To get closer tolerance, if required,
refractory bricks are machined in a six face grinding machine.
An anti-hydration treatment may be carried out to protect the bricks from
hydration and also for long storage. Finally it is to be packed, preferably
under vacuum.

MICROSTRUCTURE OF FUSED DOLOMITE BRICKS (See Fig. 2)
The brick sample made from above fused dolomite grains were examined
under microscope under reflected light after making a polished section
(2A, 2B, 2C, 2D - Magnification 200X). Section shows sub-hedral to
anhedral shape of Fericlase crystal with crystal size varying from a
minimum of <40 micron to a maximum of 330 micron with an average of 70
micron. Lime phase is present in matrix along with the Periclase crystal.
Little amount of calcium ferrite is found in the inter-granular space of the
Periclase in matrix part.
MICROSTRUCTURE OF FUSED DOLOMITE BRICKS AFTER USE IN STEEL
UNITS (See Fig. 3)
Microstructure after use in steel unit is shown in 3A, 3B, 3C, 3D
(Magnification 200X).
The brick sample after successful operation for full campaign in an AOI)
vessel were collected and evaluated for microstructure changes. The
sample was examined under microscope in a reflected light after preparing
polished section to see the changes at hot face and just inside of hot face.
Ferrite phase is found in the hot face reacting with the process material
with the brick components. Multiple small cracks are found from the hot
face which is filled with process metal. From the hot face towards cold
face periclase crystal size gradually increases. Periclase crystal size in
the hot face (up to 15 mm) is 10 micron to 50 micron with an average
crystal size of 20 micron with continuous lime matrix. Fluxing phases are
very less. In the cold face region magnesia crystal size varies from 20
micron up to 120 micron with an average crystal size of 50 micron in
continuous lime matrix. Very few grains with fine magnesia crystals are
also found in the cold face. Overall microstructure is dense with cobweb
like cracks for infiltration of steel.

Advantages of fused dolomite grains for making fused dolomite
refractories are due to their high hydration resistance, resistance to
corrosion and erosion vis-a-vis dolomite refractories made from sintered
dolomite/doloma clinkers. Fused dolomite refractory increases the life of
steel-making furnaces and vessels, and consequently results in cost-
effectiveness for steel makers as well as in non-ferrous industries.
Although the preferred embodiment of the present invention has been
disclosed for illustrative purposes, those skilled in the art will appreciate
that various modifications, additions and substitutions are possible, without
departing from the scope and spirit of the invention as recited in the
claims appended hereafter.

We claim:
1. A process for the manufacture of fused dolomite by electro fusion of
raw or calcined dolomite and articles made therefrom, characterized in
that the raw material selected for the process is of the following
composition:
(i) CaO - from 20 to 70% by weight
(ii) MgO - from 15 to 50% by weight
(iii) SiO2 - from 0.1 to 10% by weight
(iv) Fe2O3 - from 0.1 to 5% by weight
(v) Al2O3 - from 0.2 to 3% by weight
(vi) Fluorine - less than 0.2% by weight
(vii) LOI (loss on ignition) - from 40 to 50% by weight
which is subjected to calcination, if and when needed, at a temperature
of 1000 °C and raw dolomite or calcined mass is partially filled in the
base of the empty fusion pots followed by coke breeze and/or carbon
pieces, then a plurality of electrodes arc introduced in the partially
filled fusion pot, which in turn are connected by cable(s) to 1600 KVA
transformer and equipped with mechanical or hydraulic lifting devices
and a number of cycles of current is passed through the charge,,
wherein from second cycle onwards, semi-fused dolomite is fed first
into the fusion pot and then raw dolomite, preferably of 25 40 mm
size, is added at a required rate through a vibro feeder, after the
culmination of the fusion process electrodes are lifted, the fusion pot
with its contents are cooled till reaching ambient temperature, the
fused contents are taken out by being released on an inclined floor
where under-fused and semi-fused materials are sorted out and
recycled and fused dolomite mass is crushed and stored by packing in

moisture-proof bags, and the stored product may be made into
refractory bricks and shapes with the help of a suitable binder,
followed by compaction, firing and storage.
2. A process as claimed in Claim 1, wherein empty fusion pots are kept
on a trolley car under the furnace station with the help of a transfer
trolley, fusion pot base is filled with raw/calcined dolomite up to a
height of around 0.5 m, after electro fusion the pot with fused material
is taken out by Winch system to keep the trolley car on the back line
for slow cooling for over 48 hours, thereafter the pot with its contents
is taken out by overhead crane followed by further cooling of the base
for over 48 hours and then the cold fused material on the base is lifted
on a 10-degree inciined floor, the fused dolomite ingots are broken to
pieces either mechanically or manually, fused, semi-fused and under-
fused dolomite are sorted out and stacked separately, fused dolomite
lumps are crushed in a jaw crusher/rolled crusher to desired size
fraction and fused dolomite pieces are packed in moisture-proof bags,
wherein grain bulk density of fused dolomite has a minimum value of
2.98gm/cc.
3. A process as claimed in Claims 1 and 2, wherein raw/light calcined
dolomite has size fractions from 5 to 200 mm, preferably from 20 to 50
mm, or may be employed in powdered form or in the form of briquettes
or pellets made from said powdery material.
4. A process as claimed in Claims 1 and 2, wherein raw dolomite is of
Himalayan origin, accessed from Bhutan and Himalayan foothills in
India.
5. A process as claimed in Claims 1 to 4, wherein graphite electrodes are
employed in electric arc furnace to bring about electro fusion without
conventional sintering additives.

6. A process as claimed in Claims 1 to 5, wherein the fused dolomite is
converted into dolomite bricks with 100% fused dolomite grains by—
(i) crushing of fused dolomite lumps to size fraction varying
between 6 mm and 200 mesh;
(ii) hot mixing of fused grains with binder in a counter-current mixer
/ intensive mixer;
(iii) compacting the mix in a mechanical/hydraulic press to achieve
desired compaction density;
(iv) firing the refractory body at a temperature exceeding 1500 °C to
attain desired fired properties;
(v) subjecting the bricks/shapes to an anti-hydration treatment to
protect them from hydration and rendering them suitable for long
storage; and
(vi) packing the products in suitable containers, preferably under
vacuum.
7. A process as claimed in Claim 6, wherein the bricks/shapes after firing
are machined in a six face grinding machine to achieve closer
tolerance.
8. A process as claimed in Claims 1 to 4, wherein raw material employed in
the production of fused dolomite has the undernoted composition:
(i) CaO : from 50% - 70%, preferably in the range 50 - 60% by
weight;
(ii) MgO : from 35% to 50%, preferably in the range 40 - 45% by
weight;
(iii) SiO2 : from 0.1 to 5%, preferably below 1%;

(iv) Fe2O3 : from 0.1 to 5%, preferably below 1%;
(v) Al2O3 : from 0.2 to 3%, preferably below 1%; and
(vi) Fluorine content : less than 0.2%.
9. A process as claimed in Claims 6 to 8, wherein refractory bricks and
monolithics made from fused dolomite obtained by electro fusion of
raw/ calcined dolomite find application in iron and steel, as well as in
non-ferrous industries.
10. A process for the manufacture of fused dolomite by electro fusion of
raw or calcined dolomite and articles made therefrom, substantially as
hereinbefore described with particular reference to the accompanying
drawings.