Claims:1. A ceramic membrane comprising LD slag, boric acid, sodium metasilicate, sodium carbonate and alumina.

2. The ceramic membrane as claimed in claim 1, wherein the LD slag is in an amount ranging from about 45%to 55%, the boric acid is in an amount ranging from about 5%to 10%, the sodium metasilicate is in an amount ranging from about 10%to 15%, the sodium carbonate is in an amount ranging from about 10% to 20% and the alumina is in an amount ranging from about 5%to 10%.

3. The ceramic membrane as claimed in claim 1, wherein the LD slag comprises iron in an amount ranging from about 18 wt% to 19 wt%, silicon dioxide in an amount ranging from about 12.4 wt% to 12.8 wt%, aluminium oxide in an amount ranging from about 0.93 wt% to 1 wt%, calcium oxide in an amount ranging from about 48.8 wt% to 53.5 wt%, magnesium oxide in an amount ranging from about 9.83 wt% to 10.1 wt%, manganese oxide in an amount ranging from about 0.57 wt% to 0.62 wt%, phosphorus pentoxide in an amount ranging from about 2.34 wt% to 2.41 wt%, sulphur in an amount ranging from about 0.03 wt% to 0.04 wt% and free lime in an amount ranging from about 2.7 wt% to 9 wt%.

4. The ceramic membrane as claimed in claim 1, has an average pore diameter ranging from about 0.73µm to 1.77 and has porosity ranging from about 55.5% to 31.13%.

5. The ceramic membrane as claimed in claim 1, wherein the ceramic membrane is devoid of cracks.

6. A process of preparing the ceramic membrane as claimed in claim 1, comprising-
mixing the LD slag, the boric acid, the sodium metasilicate, the sodium carbonate and the alumina, followed by milling to obtain a mixture;
contacting the said mixture with a solvent to obtain a paste; and
molding the paste and incubating the mold to obtain the ceramic membrane.

7. The process as claimed in claim 6, wherein the milling is carried out for a period ranging from about 2hoursto 4hoursat a rotational speed ranging from about 200rpm to 500rpm; and wherein the solvent is Millipore water.
8. The process as claimed in claim 6, wherein the mold comprising the paste is incubated for a period ranging from about 10hours to 12hours, under influence of weight ranging from about 2kg to 4kg.

9. The process as claimed in claim 6, further comprises-
drying the obtained ceramic membrane at a temperature ranging from about 110°C to 200°C for a period ranging from about 8hoursto 12hours; and
sintering the ceramic membrane at a temperature ranging from about 700°C to 1000°C.

10. The process as claimed in claim 9, further comprises-
polishing the ceramic membrane, followed by sonicating the ceramic membrane;
incubating the ceramic membrane in water for a period ranging from about 8hoursto 20hours; and
pat drying the ceramic membrane, followed by incubating the ceramic membrane in an oven for a period ranging from about 12hoursto 24hours.

11. The process as claimed in claim 10, wherein the polishing is carried out by polishing paper selected from a group comprising SiC abrasive paper and C-22 polishing paper; and the sonication is carried out for a period ranging from about 20minutes to 30minutes.
, Description:TECHNICAL FIELD
The present disclosure relates to field of material science. The disclosure particularly relates to LD slag (by product of Linz-Donawitz process) based ceramic membrane. The present disclosure further relates to process of preparing the said ceramic membrane. The disclosure also relates to use of the said ceramic membrane in the preparation of system for filtration, wastewater purification and clarification.

BACKGROUND OF THE DISCLOSURE
The slag generated during the steel making process in the basic oxygen converter is one of the primary wastes. The slag is basically produced by a process that converts pig iron into workable steel. Reuse of waste generated during steel making process is important with regard to environmental and economic consideration. The slag generated from basic oxygen converter (LD-slag) is known to be reused in roadmaking due to its high hardness and cementing property.

Though, the LD-slag can be used in metallurgical purposes for iron making and steel making, the high phosphorous content in the LD-slag restricts its use in iron making and steel making.
As a result, it is noted that effective utilization of the LD-slag can be achieved only upon removal of phosphorous from the LD-slag. Upon removal of phosphorus, the LD-slag can be recycled in steelmaking as a flux material and also can be charged in blast furnace in place of lime stone. For effective utilization of the LD-slag and in order to reduce the disposal cost of the LD-slag, there is a need of further processing of the LD-slag, which is increasing the processing cost and not turning out to be economical indeed.

So, there is a need for effective utilization of the LD-slag without incurring the processing cost, such that there is also no need to incur cost for disposing LD-slag.

The Applicants of the present disclosure intend to solve the above said problems such as need for further processing of the LD-slag for effective utilization of the slag or the cost associated with disposing the LD-slag and environmental hazard due to disposal of the slag, by effectively utilizing the LD-slag for generation of an economically useful product.

SUMMARY OF THE DISCLOSURE
The object of the present disclosure is to utilize the LD-slag waste into generation of an economically useful product.
The present disclosure relates to LD slag based ceramic membrane, wherein the LD-slag obtained from the steel making process is directly employed into preparation of the ceramic membrane.

The ceramic membrane of the present disclosure comprises LD-slag, boric acid, sodium metasilicate, sodium carbonate and alumina.

The present disclosure further relates to a process of preparing the said ceramic membrane, comprising- mixing the LD-slag, the boric acid, the sodium metasilicate, the alumina, followed by ball milling to obtain a mixture; contacting the mixture with a solvent to obtain a paste; and molding the paste, followed by incubating the mold to obtain the ceramic membrane.

The present disclosure furthermore relates to use of the said ceramic membrane in preparation of system for filtration, wastewater treatment, desalination and clarification.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the present disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure where:

FIGURE 1 illustrates Field emission scanning electron microscope (FESEM) images of the ceramic membrane of the present disclosure sintered at 700°C (a) and at 800°C (b), respectively.

FIGURE 2 illustrates Energy Dispersive X-ray (EDX) spectrum of the ceramic membrane depicting the presence of elements such as, calcium, magnesium, silicon, sodium, manganese, sulphur, iron and potassium.

FIGURE 3 illustrates Energy Dispersive X-ray spectroscopy (EDS) mapping of the ceramic membrane.

FIGURE 4 illustrates X-ray powder diffraction (XRD) spectrum of the ceramic membrane. The phases [111], [200] and [222] in the spectrum corresponds to calcium oxide, dicalcium silicates.

FIGURE 5 illustrates variation in porosity of the ceramic membrane when subjected to sintering at temperature ranging from about 700°C to 1000°C.

FIGURE 6 illustrates pore size variation of the ceramic membrane at sintering temperature ranging from about 700°C to 1000°C, wherein ‘1’ represents the pore size calculation obtained by J software technique and ‘2’ represents the pore size calculation obtained by water permeation technique.

DETAILED DESCRIPTION OF THE DISCLOSURE
The present disclosure relates to LD-slag (by product of Linz-Donawitz process) based ceramic membrane.

In an embodiment, the ceramic membrane comprises LD-slag, boric acid, sodium metasilicate, sodium carbonate and alumina.

In an embodiment, the ceramic membrane comprises the LD-slag in an amount ranging from about 45wt% to 55 wt%.

In another embodiment, the ceramic membrane comprises the LD-slag in an amount of about 45wt%, about 46wt%, about 47wt%, about 48wt%, about 49wt%, about 50wt%, about 51wt%, about 52wt%, about 53wt%, about 54wt% or about 55wt%.

In an embodiment, the ceramic membrane comprises the boric acid in an amount ranging from about 5wt% to 10wt%.

In another embodiment, the ceramic membrane comprises the boric acid in an amount of about 5wt%, about 6wt%, about 7wt%, about 8wt%, about 9wt% or about 10wt%.

In an embodiment, the ceramic membrane comprises the sodium metasilicate in an amount ranging from about 10 wt% to 15 wt%.

In another embodiment, the ceramic membrane comprises the sodium metasilicate in an amount of about 10wt%, about 11wt%, about 12wt%, about 13wt%, about 14wt% or about 15wt%.

In an embodiment, the ceramic membrane comprises the sodium carbonate in an amount ranging from about 10wt% to 20wt%.

In another embodiment, the ceramic membrane comprises the sodium carbonate in an amount of about 10wt%, about 11wt%, about 12wt%, about 13wt%, about 14wt%, about 15wt%, about 16wt%, about 17wt%, about 18wt%, about 19wt% or about 20wt%.

In an embodiment, the ceramic membrane comprises the alumina in an amount ranging from about 5wt% to 10wt%.

In another embodiment, the ceramic membrane comprises the alumina in an amount of about 5wt%, about 6wt%, about 7wt%, about 8wt%, about 9wt% or about 10wt%.

In an embodiment, the LD-slag comprises iron in an amount ranging from about 18 wt% to 19 wt%, silicon dioxide in an amount ranging from about 12.4 wt% to 12.8 wt%, aluminium oxide in an amount ranging from about 0.93 wt% to 1 wt%, calcium oxide in an amount ranging from about 48.8 wt% to 53.5 wt%, magnesium oxide in an amount ranging from about 9.83 wt% to 10.1 wt%, manganese oxide in an amount ranging from about 0.57 wt% to 0.62 wt%, phosphorus pentoxide in an amount ranging from about 2.34 wt% to 2.41 wt%, sulphur in an amount ranging from about 0.03 wt% to 0.04 wt% and free lime in an amount ranging from about 2.7 wt% to 9 wt%.

In an embodiment, the ceramic membrane is porous in nature with an average pore diameter ranging from about 0.73µm to 1.77 µm.

In another embodiment, the ceramic membrane has an average pore diameter of about 0.73µm, about 0.73µm, about 0.83µm, about 0.93µm, about 1.03µm, about 1.13µm, about 1.23µm, about 1.33µm, about 1.43µm, about 1.53µm, about 1.55µm, about 1.57µm, about 1.59µm, about 1.61µm, about 1.63µm, about 1.65µm, about 1.67µm, about 1.69µm, about 1.71µm or about 1.73µm.

In an embodiment, the ceramic membrane has porosity ranging from about 31.13% to 55.5%.
In another embodiment, the ceramic membrane has porosity of about 31.13%, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, about 40%, about 41%, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50%, about 51%, about 52%, about 53%, about 54%, about 55%, about 55.1%, about 55.2%, about 55.3%, about 55.4% or about 55.5%.

In an embodiment, the ceramic membrane of the present disclosure is devoid of cracks.

In an embodiment, the ceramic membrane is stable at temperature ranging from about 700°C to 1000°C.

In another embodiment, the ceramic membrane is stable at temperature of about 700°C, about 720°C, about 740°C, about 760°C, about 780°C, about 800°C, about 820°C, about 840°C, about 860°C, about 880°C, about 900°C, about 920°C, about 940°C, about 960°C, about 980°C or about 1000°C.

In an embodiment, the ceramic membrane is defect free, is stable and strong enough to carry out filtration process at temperature ranging from about 700°C to 800°C.

In another embodiment, the ceramic membrane is defect free, is stable and strong enough to carry out filtration process at temperature of about 700°C, about 710°C, about 720°C, about 730°C, 740°C, about 750°C, about 760°C, about 770°C, 780°C, about 790°C or about 800°C.

In an embodiment, the ceramic membrane is in a form such as, disk shape, Rectangular Shape for cross flow analysis and tubular shape for module preparation.

In an embodiment, the ceramic membrane of the present disclosure has enhanced temperature resistivity, enhanced mechanical strength and enhanced separation efficiency.

In an embodiment, the figure 1 illustrates the surface morphology of the ceramic membrane when sintered at a temperature of about 700°C and at a temperature of about 800°C, respectively.

In an embodiment, the figure 2 illustrates the Energy Dispersive X-ray studies of the ceramic membrane depicting presence of elements such as, calcium, magnesium, silicon, sodium, manganese, sulphur, iron and potassium.

In an embodiment, the figure 3 illustrates the Energy dispersive X-ray (EDS) mapping of the ceramic membrane.

In an embodiment, the figure 4 illustrates the X-ray powder diffraction of the ceramic membrane, wherein the phases [111], [200] and [222] correspond to presence of calcium oxide, dicalcium silicates in the ceramic membrane.

In an embodiment, the figure 5 illustrates the variation in porosity of the ceramic membrane ranging from about 55.5% to 31.13% at sintering temperature ranging from 700°C to 1000°C.

In an embodiment, the figure 6 illustrates the pore size in the ceramic membrane obtained using the image J software technique (1) and the water permeation technique (2). As per the figure, the pore size in image J software calculations are high as compared to water permeation technique. This is due to the fact that software calculations considered only the surface diameter of the pores considering all the pores to be open. Whereas, pores may not be continuous in actual cases as evidently obtained by permeation tests.

The present disclosure relates to process of preparing the ceramic membrane.

In an embodiment, the process of preparing the ceramic membrane comprises-
mixing the LD-slag, the boric acid, the sodium metasilicate, the sodium carbonate and the alumina, followed by milling to obtain a mixture;
contacting the said mixture with a solvent such as, millipore water to obtain a paste; and
molding the paste and incubating the mold to obtain the ceramic membrane.

In another embodiment, the process of preparing the ceramic membrane comprises-
mixing the LD-slag, the boric acid, the sodium metasilicate, the sodium carbonate and the alumina, followed by milling to obtain a mixture;
contacting the said mixture with a solvent such as, millipore water to obtain a paste; and
molding the paste and incubating the mold to obtain the ceramic membrane.
wherein the obtained ceramic membrane is subjected to treatment/further processing such as, drying, sintering, polishing and sonicating.

In an embodiment, the mold comprising the paste is incubated for a period ranging from about 10hours to 12hours, under influence of weight ranging from about 4kg to 6kg.

In another embodiment, the mold comprising the paste is incubated for period of about 10hours, about 10.5hours, about 11hours, about 11.5hours or about 12hours, under influence of weight of about 2kg, about 2.5kg, about 3.0kg, about 3.5kg or about 4kg.

In an embodiment, the ceramic membrane is removed from the mold and subjected to drying in an oven at a temperature ranging from about 110°C to 200°C for a period ranging from about 8hrsto 12hrs, followed by sintering at a temperature ranging from about 700°C to 1000°C.

In another embodiment, the ceramic membrane is removed from the mold and subjected to drying in an oven at a temperature ranging from about 110°C, about 120°C, about 130°C, about 140°C, about 150°C, about 160°C, about 170°C, about 180°C, about 190°C or about 200°C, for a period of about 8hours, about 9hours, about 10hours, about 11hours or about 12hours.

In another embodiment the ceramic membrane is subjected to sintering at a temperature of about 700°C, about 720°C, about 740°C, about 760°C, about 780°C, about 800°C, about 820°C, about 840°C, about 860°C, about 880°C, about 900°C, about 920°C, about 940°C, about 960°C, about 980°C or about 1000°C.

In an embodiment, after sintering the ceramic membrane, the ceramic membrane is subjected to polishing using polishing paper selected from a group comprising C-22 polishing paper and SiC abrasive paper. The polished ceramic membrane is subjected to sonication in water for a period ranging from about 20minutes to 30minutes. Sonication is carried out to remove any powder on the ceramic membrane surface as a result of polishing.

In another embodiment, the sonication is carried out for a period of about 20minutes, about 21minutes, about 22minutes, about 23minutes, about 24minutes, about 25minutes, about 26minutes, about 27minutes, about 28minutes, about 29mintues or about 30minutes.

In an embodiment, after sonication, the ceramic membrane is submerged in water for a period ranging from about 8hours to 20hours in order to remove unwanted leachate. After incubating the ceramic membrane under water, the ceramic membrane is subjected to drying such as, pat drying and incubated in oven at a temperature ranging from about 150°Ccto 200°Cfor a period ranging from about 12hours to 24_hours, for removing moisture and water.

In another embodiment, the ceramic membrane is submerged in water for a period of about 8hours, about 9hours, about 10hours, about 11hours, about 12hours, about 13hours, about 14hours, about 15hours, about 16hours, about 17hours, about 18hours, about 19hours or about 20hours.

In another embodiment, the pat drying and incubation is carried out at a temperature of about 150°C, about 160°C, about 170°C, about 180°C, about 190°C or about 200°C.

In an embodiment, the milling is ball milling carried out for a period ranging from about 1hours to 2 hours at a rotational speed ranging from about 800rpm to 1000rpm.

In another embodiment, the ball milling is carried out for a period of about 1hours, about 1.5hours or about 2hours at a rotational speed of about 800rpm, 850rpm, 900rpm, 950rpm or about 1000rpm.

The present disclosure further relates to use of the ceramic membrane in the preparation of filtration system.

In another embodiment, the disclosure relates to use of the ceramic membrane in the preparation of microfiltration system.

In another embodiment, the disclosure also relates to use of the ceramic membrane in the preparation of system for water treatment, clarification, desalination and purification.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon the description provided. The embodiments provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments. The examples provided herein are intended merely to facilitate an understanding of ways in which the embodiments provided may be practiced and to further enable those of skill in the art to practice the embodiments provided. Accordingly, the following examples should not be construed as limiting the scope of the embodiments.

EXAMPLES

EXAMPLE 1: Preparation of the ceramic membrane.
About 55wt% of LD-slag, about 5wt% of boric acid, about 15wt% of sodium metasilicate, about 15% sodium carbonate and about 10wt% of alumina was mixed and grounded in a ball mill for about 2 hours at about 200rpm to obtain a mixture.
The obtained mixture was mixed with Millipore water to obtain a paste of a definite consistency for molding into a disk shaped membrane. Once the desired paste was obtained, it was cast onto SS-ring mold and kept under a uniform weight of about 4kg for period of about 10hours to 12hours.

The ceramic membrane was removed from the SS-ring mold carefully and was dried in an oven at a temperature of about 110°C for a period of about 12hours to remove the moisture and additional water present in the obtained disk shaped ceramic membrane.
The ceramic membrane was subjected to sintering at a temperature ranging from about 700°C to 1000°C, followed by polishing the ceramic membrane using a C-22 polishing paper.
The polished membrane was sonicated in water for a period of about 30 minutes to remove the powder on the membrane surface as a result of polishing and then kept submerged in water for a period of about 12hours to remove unwanted leachate.
Further, the ceramic membrane was pat dried and then incubated in oven at a temperature of about 250°C for a period of about 12hours to remove moisture and water.

EXAMPLE 2: Application of the ceramic membrane in the microfiltration system.
The ceramic membrane was employed for microfiltration before tertiary treatment of desalination. The wastewater containing chloride content up to 4000ppm undergoes microfiltration step before subjecting to nanofiltration to remove any iron and heavy metals. The presence of iron and heavy metals will create detrimental effect on nanofiltration membranes. The ceramic membrane of the present invention removes the iron and the heavy metals impurities effectively and efficiently during microfiltration. The results are tabulated in the table below.

The ceramic membrane was tested under the filtration capacity of about 300ml, at pressure of about 103KPa, about 117KPa and 196KPa, respectively.

Table 1: Application of Ceramic membrane for microfiltration before tertiary treatment.