The present invention is directed to process of manufacturing bricks, blocks or paver blocks, and more particularly to an eco-friendly method of manufacturing bricks or blocks from brine sludge generated as waste in membrane chloralkali industry.
BACKGROUND OF INVENTION
[0002] In a membrane chloralkali industry, industrial grade salt has been widely known as one of the major raw materials that gets dissolved in water/depleted brine The brine along with impurities such as calcium, magnesium and other insolubles are separated using chemicals such as sodium carbonate or sodium hydroxide or the removal of the calcium and magnesium impurities. After the treatment these impurities calcium and magnesium salts are precipitated.
[0003]The brine with insoluble impurities is allowed to settle in a clarifier wherein the clarified brine is obtained leaving behind all the insoluble precipitates settled at the bottom of the clarifier as sludge, commonly known as the brine sludge (mud), which is of non-hazardous nature. However, till date the brine sludge has been either used for the preparation of bunds in the solar salt fields, or land fill or stored in secured pits.
[0004] Given the increasing obligations of both the government and the citizens to preserve, protect and conserve the environment, need of the hour is to convert existing industrial processes into greener ones so that sustainability aspect of the environment can be secured without compromising on the profitability of establishments.

[0005] Techniques for making bricks have been known for thousands of years. In recent years many individual steps in the process of brick making and apparatus for handling the materials have been developed and improved. However, existing brick making processes have not focused much on utilizing the wastes of other industry which might be put to some beneficial use rather than being discarded away.
OBJECT OF THE INVENTION
[0006] The primary objective of the present disclosure is to devise an eco-friendly process of manufacturing bricks or blocks or paver blocks.
[0007] In one other objective of the present disclosure, the less complex brick or block making process utilizes brine sludge that gets settled as an impurity at the brine treatment phase in a membrane chloralkali industry.
[0008] Another objective of the present disclosure is to provide an economized process of utilizing non-hazardous brine sludge or mud to make a saleable product.
[0009] Another objective of this disclosure is to recover the calcium and magnesium salts of brine sludge that otherwise gets discarded in a membrane chloralkali industry so as to manufacture suitable construction material such as bricks, paver blocks or solid blocks.
[0010] Yet another objective of the disclosure is to suitably utilize the spent acid, also generated as a waste in membrane chloralkali industry, to reduce pH of sludge and make it more amenable for preparing concrete mix to be used in construction material.

[0011] Still another objective of the disclosure provides a green mechanism for manufacturing bricks, blocks or paver blocks having compressive strengths and water absorption properties equivalent to that of clay bricks.
SUMMARY OF THE INVENTION
[0012] The present invention is directed to a method of manufacturing brick blocks from brine sludge that is released from membrane chloralkali industry as a waste. The steps of manufacturing include adjusting pH levels of the brine sludge between a predetermined range; adding cement, aggregates, manufactured sand or fly ash a combination thereof to the treated brine sludge and obtain a mix; and curing the mix with water to obtain the brick blocks.
[0013] These and other aspects, features and advantages of the present invention will be described or become apparent from the following detailed description of preferred embodiments.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0014] Before the present process of manufacturing brick/blocks or paver blocks is described, it is to be understood that this disclosure is not limited to the particular method or process for achieving so, as described, since it may vary within the specification indicated. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only,

and is not intended to limit the scope of the present invention, which will be limited only by the appended claims.
[0015] The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. The disclosed embodiments are merely exemplary methods of the invention, which may be embodied in various forms.
[0016] In a Chloralkali Industry, products such as caustic soda, chlorine, hydrogen, hydrochloric acid &sodium hypochlorite are produced through membrane electrolysis. There are various technologies through which these products are known to be produced, one of the latest being the “membrane technology” which is environment-friendly, mercury free and energy efficient.
[0017] During clarification process, the clarified brine is obtained while the insoluble impurities are allowed to settle at the bottom as brine sludge (mud). Typically, the brine sludge comprises of calcium carbonate (13 - 18 %), magnesium hydroxide (1.5 – 11 %), silica/insolubles (11.5 - 29%), iron hydroxide (3.8 – 11%) and moisture (31 - 36%). However, the brine sludge of different composition with varying soluble impurities is also suitable for current process, discussed later in the description.
[0018] The brine sludge generated from the membrane chloralkali plant is non-hazardous in nature, and its composition varies with the quality of the salt and the

process of separation of sulphate from the brine stream. In order to make this process greener, a process to convert the brine sludge or mud into a saleable product is conceptualized.
[0019] As popularly known that the sludge comprises of calcium and magnesium salts, it is an apt material for making construction material such as bricks, paver blocks or solid blocks. The solid sludge is mixed with cement and aggregates or manufactured-sand, chips followed by curing the bricks in water either by soaking or sprinkling with water on the bricks/blocks and finally drying to achieve the end product.
[0020] However, prior to mixing, the brine sludge or mud is treated for particle size enhancement by reducing the pH of the sludge to 5.0 - 12 to make the sludge more amenable for the concrete mix. Here, the spent acid such as the sulphuric acid (concentration 30 – 98 %) /Hydrochloric acid (10 – 33%) or any acid of varying concentration which is generated as a waste in a Chloralkali plant is being used. The process of producing bricks/blocks from the sludge also consumes the waste acids produced in the Chloralkali Industry, thus making the process greener as both the wastes are converted to saleable and useable products.
[0021] The composition of sludge in the concrete mix is varied between 30 – 50 % in combination with cement and aggregates, chips, manufactured-sand (M-sand) or fly ash. The mix with the varying compositions is cast and cured with water and dried to achieve the compressive strength of the bricks as equivalent to clay bricks. The curing process comprises of immersing the units in water or wetting by means of gunny bags

or hay or sprinkling of water. The curing time is varied between 5 – 30 days, and the bricks and blocks after curing is allowed to dry for 1 – 5 days.
[0022] The principles of the present invention may be best illustrated by process steps discussed herein now in detail. At first, the sludge removed from the filter press is measured and taken for treatment for the particle size modification. In one preferred embodiment of present disclosure, spent sulphuric acid/hydrochloric acid or any mineral acid is added for bringing down the pH from 5-12. The mixture is then allowed to react for 2 – 24 hrs.
[0023] The mix after the completion of the reaction is mixed with the measured quantity of cement and aggregates, say for example, 3 – 12 mm aggregates or M-Sand depending on the availability. The mixture is mixed thoroughly for uniform consistency with addition of minimum water and kept in wooden or plastic moulds of varying sizes that is commercially available in the market. A small vibrator is used for setting of the mix in the moulds. The moulds are generally left undisturbed for 1 – 12hrs and then released. The casted bricks/blocks are allowed to stand for 2 – 24 hrs and then immersed in the water or soaked/sprinkled with water.
[0024] In one exemplary embodiment, the bricks are cured in water for a period 5 – 30 days to study the compressive strength and the water absorption properties. Also, the composition of the sludge in the mix is varied between 30 – 50 % and studied for the compressive and the water absorption tests. The results of these tests are illustrated herein below in Table 1.

[0023] The Table 1 explains the result itself as good quality bricks and blocks are formed having a compressive strength of more than 40 kgs/cm2 (3.92 N/mm2) and the water absorption of < 20 %.
[0024] In one other preferred embodiment all three type of products namely bricks, paver blocks, and solid blocks are manufactured. As discussed above, at first the sludge is mixed with cement and aggregates or M-sand and made into a uniform consistency mix. It is then poured into moulds and allowed to stand for 0.5 -12 hrs. The blocks/bricks are released from the moulds, and cured under water or wetting or sprinkling with water approximately 24 hrs later. The curing time can be varied between 5 – 30 days.
[0025] Table 2 given below provides the result of performance testing of the final product. For example, the bricks/paver blocks/solid blocks are tested for consistency in the results and durability, compressive strength and the water absorption property. The sludge is also tested for toxicity characteristics and has been determined as non-hazardous.

machine fabrication unit on large scale production trial is tested, the results of which are discussed in Table 3 here below:

5 [0027] The bricks made with aforementioned process can be used for normal civil construction and be a substitute for the concrete blocks available in the market. They have a good compressive strength ranging between 30 – 140kgs/sq.m (approx. 3 – 6 Mpa) with a water absorption capacity of 7- 20 %. Bricks or blocks of varying sizes (mm) (LXBXH) and shapes/designs can be made depending upon the requirement: Bricks 10 :230X100X75, Blocks (6”) : 400 X 150 X 195, Blocks (8”) : 400X200X200, Paver blocks : a) 195 X 195 X 60 (thk) b) 240 X190 X 80 mm (thk).

[0028] Further, the blocks / bricks can be made with or without the soluble impurities from the brine sludge/mud with a compressive strength of 30 – 60 kgs/sq.cm (3 – 6 MPa). The properties of bricks/blocks made are much better than the commercially available product with respect to the compressive strength and the water absorption.
[0029] The exemplary methods and acts described in the embodiments presented previously are illustrative, and, in alternative embodiments, certain acts can be performed in a different order, in parallel with one another, omitted entirely, and/or combined between different exemplary embodiments, and/or certain additional acts can be performed, without departing from the scope and spirit of the invention. Accordingly, such alternative embodiments are included in the inventions described herein.

We Claim:
1) A method of manufacturing brick blocks from brine sludge, comprising:
adding cement, aggregates, manufactured sand or fly ash a combination thereof
to brine sludge and obtain a mix; and
curing the mix with water to obtain the brick blocks.
2) The method according to claim 1, further comprising adjusting pH levels of the brine sludge between a predetermined range.
3) The method according to claim 2, wherein the pH of the brine sludge is maintained within the predetermined range of 5-12 by adding one or more acids.
4) The method according to claim 3, wherein the acid added to maintain the pH of the brine sludge is sulphuric acid of concentration varying between 30-98% or hydrochloric acid of concentration ranging between 10-33% or a combination thereof.
5) The methodaccording to claim 1, wherein the pH levels of the brine sludge are maintained for enhancement of particle size thereof.
6) The methodaccording to claim 1, wherein composition of the brine sludge is varied between 30%to 50%.

7) The method according to claim 1, wherein the mix obtained by addingthe cement, aggregates, manufactured sand or fly ash is allowed to stand for 2-24 hrs.
8) The method according to claim 1, wherein the mix is casted in moulds to allow setting of the mix and left for 1-12 hrs before releasing.
9) The method according to claim 1, wherein the curing of the mix is varied between 5-30 days.
10)The method according to claim 1, further comprising drying of the mix for 1-5 days after curing with the water.
11)The method according to claim 1, wherein the brine sludge comprises of calcium carbonate ranging between 13-18%, magnesium hydroxide ranging between 1.5-11%, insolubles ranging between 11-29%, iron hydroxide ranging between 3.8-11% and moisture levels between 31-36%.