|Title of Invention||
SYNTHETIC SLAG USED FOR ADJUSTING THE SIO2 CONTENT OF SLAG IN THE PRODUCTION OF HIGH CARBON FE MN IN SUBMERGED ARC FURNACE (SAF)
|Abstract||A process of producing synthetic slag used for adjusting the SiO2 content of slag in the production of high carbon FeMn in submerged arc furnace where in the quartz / quartzite fines or suitable materials. Containing high concentration of silica is mixed with stream of hot molten slag form FeMn operation and after coding; the mixture is rushed of lumps of required size for use.|
|Full Text|| The invention relates to Synthetic Slag used for adjusting the SiO2 content of slag in the production of high carbon FeMh in SAF, Submerged Arc Furnace, where FeMn Ores used are of low Silica - high aluminum type.
The Present invention is that it uses the slag generated during production of high carbon ferromanganese (HCFeMn) and quartz powder for production of synthetic slag. The concentration of SiO2 in the slag plays vital role in the smelting reduction of Mn-ores in SAF, Present practice uses blending of Mn-ore with higher concentration of SiO2 to adjust the SiO2 requirement. However, availability and cost of high Si02~Mn-ores has created many operational problems in SAF, The direct addition of quartz lumps in the furnace is. not effective due to slow dissolution -of the SiO2 in the slag due to lower operating temperatures used for HCFeMn production.. The addition of fine particles of the quartz is not possible as fines particle disturbs the bed permeability and also affects the gas cleaner plant. Therefore a novel
method has been developed for the production of high SiO2-Mn-slag, which can be used as a feed for adjusting the SiO2 demand. In this novel method, the fine quartz powder ( It's Utility:
The process developed is very economical for production of synthetic slag. The synthetic slag produced will be an important substitute for Mn-ores with high SiO2 content. The use of synthetic slag in reduction-smelting will also improve the SAF operations.
The use of synthetic slag will also minimize the furnace problems such as slag boil. It will also improve the overall Mn recovery.
The Mn-ores in Orissa are low silica - high alumina type and hence addition of high silica Mn-ores is essential for any FeMn production process. Since high silica Mn-ores are expensive and are in short supply, this novel process will be techno-economically viable options for all FeMn producers who process Mn-ores from Orissa. Therefore the commercialization of this process will have significant value to the FeMn producers.
Background and the process
Ferromanganese is produced conventionally by smelt ing-reduction process in submerged arc furnace (SAF). Most of the Mn-ores mined in Orissa are inherently suitable for FeMn production but contains significant amount of alumina. For SAF process, the high amount of silica is required to dissolve the alumina in the slag and to reduce the liquidus temperature of the slag. Unfortunately the silica content in Orissa Mn-ores is less as
compared those found in Central India (MOIL). For adjustment of silica content in the charge the Mn-ore from different mines are blended with Si-rich ores (mainly form MOIL). Quartz/quartzite used a silica additive in FeCr production can be used in the production of FeMn as the operation temperatures used for FeMn production are below 1500 C whereas FeCr production temperature are >1700 C. The rate of dissolution of quart lumps in the SAF is very slow at lower temperature. In addition to that addition of quart fines for faster dissolution is not possible, as SAF operation needs charge in the lumpy/agglomerated form.
The invention is described with reference to the
Fig.l. Shows the black diagram of the flow chart of
the new process.
Fig.2. shows the effect of Silica addition on the
Composition of slag for production of the synthetic
slag at 1200 C.
Therefore, a novel process is developed for adjusting the silica levels in the SAF charge for production of FeMn
from Orissa Mn-ores. The process flow chart of the new
process is presented in Figure 1. The high-silica
synthetic slag is produced by mixing the quartz/quartzite fines or any suitable materials containing high concentration of silica with hot molten slag from FeMn operation (1) during tapping the sensible heat of the slag will assist the rapid dissolution of the quartz fines. Rise in concentration of silica in the slag will reduce the liquids temperature of slag, which in turn will help to keep the flow of slag through runner. Undissolved. quartz particles will get agglomerated in the molten slag and thereby it will eliminate the fines formation on the top side of the furnace after charging as a additive. The addition of quartz fines in the molten slag has following advantages;
1) Recycling of high-Mn slag in this form will improve
the overall recovery of the process.
2) Minimize the operational difficulties in the SAF
3) Process will use waste heat from the slag for
production of synthetic additional energy is required.
In this process silica containing fine powder
(quartz, quartzite, silica sand, etc.) is first
dried to remove the moisture. The controlled
amount dried powders "(6) are then mixed with the stream of the hot molten slag (3) flowing through the runners and casting moulds.
The riowing siag heip to mix the fine powders with slag and thereby improves the mixing, dissolution reaction, and also agglomeration process. The process can absorb (chemically and physically) silica in the range of 10-30% and produce synthetic slag with silica content in the range of 30 to 45%. The results of computation of silica addition in FeMn slag are shown in Figure 2. The slag after cooling is then crushed to lumps of required size(5). No separation off quartz fines was observed during crushing stage. The addition of synthetic slag lumps in SAF does not affect the SAF operations and improve the slag formation in the early stages of reduction process and thereby enhances the smelting-reduction reaction of Mn-ores.
1) A process of producing synthetic slag used for adjusting the SiO2 content of slag in the production of high carbon FeMn in submerged Arc Furnace (SAF) where in the quartz/quart zite fines or suitable materials containing high concentration of silica is mixed with the stream of hot molten slag from FeMn operation and after cooling, the mixture is crushed to lunps of required size for use.
2) A process as claimed in claim-1, wherein the
material containing high concentration of
silica, is first dried to remove moisture
before use in the process and controlled
amount of dried fines are mixed with the
stream of the hot molten slag flowing through
the runners and casting moulds.
3) A process as claimed in claim-2f wherein the
flowing slag help to mix the fine powders
with slag and thereby improves the mixing,
dissolution reaction, and also agglomeration
4) A process as claimed in claim-3 wherein the
absorption of silica chemically and
physically is in the range 10 to 30% and the
silica content present in the synthetic slag
produced in the process is in range of 30 to
* IT ft
5) A process as claimed in any of the claims
wherein the synthetic slag produced at the
end of the process can be used through
recycling the slag into the submerged are
furnace or can be supplied to the other FeMn
6) Synthetic slag produced by the process as
claimed in any of claims 1 to 5,
7) A process of producing synthetic slag used
for adjusting the SiO2 content of slag in the
production of high carbon FeMn in submerged
Arc Furnace is substantially here in
described in description and illustrated in
|Indian Patent Application Number||1025/KOL/2006|
|PG Journal Number||11/2013|
|Date of Filing||05-Oct-2006|
|Name of Patentee||TATA STEEL LIMITED,|
|Applicant Address||Jamshedpur 831001,India|
|PCT International Classification Number||N/A|
|PCT International Application Number||N/A|
|PCT International Filing date|