Title of Invention	PROCESS FOR INCREASING SOLID CONTENT OF RAW SLURRY
Abstract	This invention discloses a process for increasing solid content of raw slurry, characterized in that a raw slurry concentrating equipment is added behind a hydro cyclone grading procedure on the basis of the conventional process, wherein the process includes: the raw slurry from the grading overflow port of the hydro clone in the present raw milling procedure, which has a solid content of 250 to 300g/l, is sent to the added hydro clone for concentration, the concentrated underflow raw slurry has a solid content of up to 600 to 800g/l and is sent as a product of this procedure to the normal pressure desilication procedure; and the concentrated overflow from the hydro clone is returned to the intermediate pump tank for cycle grading and concentrating.. This invention is capable of efficiently increasing the solid content of raw shurry, improving the technical indexes of the desilication procedure, and saving engineering investment. This invention is used in the raw milling procedure in alumina factories.

Title of Invention

PROCESS FOR INCREASING SOLID CONTENT OF RAW SLURRY

Abstract

This invention discloses a process for increasing solid content of raw slurry, characterized in that a raw slurry concentrating equipment is added behind a hydro cyclone grading procedure on the basis of the conventional process, wherein the process includes: the raw slurry from the grading overflow port of the hydro clone in the present raw milling procedure, which has a solid content of 250 to 300g/l, is sent to the added hydro clone for concentration, the concentrated underflow raw slurry has a solid content of up to 600 to 800g/l and is sent as a product of this procedure to the normal pressure desilication procedure; and the concentrated overflow from the hydro clone is returned to the intermediate pump tank for cycle grading and concentrating.. This invention is capable of efficiently increasing the solid content of raw shurry, improving the technical indexes of the desilication procedure, and saving engineering investment. This invention is used in the raw milling procedure in alumina factories.

Full Text	Process for Increasing Solid Content of Raw Slurry Technical Field This invention relates to an alumina production process for use in the raw material grinding procedure in alumina factories. Background Art In the raw material grinding procedure in alumina factories using Bayer process, bauxite, lime, and a part of recycling spent liquor are fed together into a raw mill in a certain proportion for grinding. The slurry after the grinding is graded by means of a hydroclone or a spiral grader The graded underflow is returned to the raw mill for fine grinding again. The graded overflow is sent as raw slurry to the normal pressure desilication procedure in a digesting workshop for normal pressure desilication. Suppose a hydroclone is used for grading of raw slurry, the solid content into the hydrocyclone is 400 to 550g/l; the solid content of the underflow of the hydrocyclone is 800 to lOOOg/1; and the solid content of the overflow is 250-300 g/1. The solid content index of the subsequent normal pressure desilication procedure is affected by the solid content of the overflow of the hydrocyclone of the raw mill and thus cannot be improved by the present procedure. The main technical indexes in the normal pressure desilication procedure in production at present include; desilication solid content is around 300g/l; the desilication temperature is 100 to 105°C; and the desilication time is 8 to 12 hours. Spoken from process, solid content is one of the important indexes that affect the desilication effect of aluminum ores. The results of the processing performance tests for bauxites at various regions show that the desilication solid content is proportional to the desilication rate of bauxites. The higher the solid content is, the higher the desilication rate is, and the better the effect of the normal pressure desilication effect is. The desilication solid content that is generally recommended by the test report is 600 to 800g/l. The present raw milling procedure is affected by the grader, and the solid content of the raw slurry at present can only reach to 250 to 300 g/1, which cannot meet the requirement of 600 to 800 g/1 recommended in the test report. Summary of the Invention The object of this invention is to raise a process for increasing the solid content of raw slurry, which uses a new concentration process by a hydroclone to increase the solid content of raw slurry sent to the normal pressure desilication procedure to 600 to 800 g/1 to increase the desilication efficiency of the raw slurry while reduce the investment in normal pressure desilication procedure. This invention is thus realized: a raw slurry concentrating equipment is added behind a hydrocyclone grading procedure on the basis of the conventional process, wherein the process includes: the raw slurry from the grading overflow port of the hydroclone in the present raw milling procedure, which has a solid content of 250 to 300g/l3 is sent to the added hydroclone for concentration; the concentrated underflow raw slurry has a solid content of up to 600 to 800g/l and is sent as a product of this procedure to the normal pressure desilication procedure; and the concentrated overflow from the hydroclone is returned to the intermediate pump tank for cycle grading and concentrating. The raw slurry concentration establishment adopts the concentration manner of using a hydroclone. The specification of the hydroclone is 300 to 500. The foregoing process has the following main technical indexes: (1) The hydroclone concentration procedure: the solid content of the feed of the hydroclone is 250 to 300 g/1; the pressure of the feed of the hydroclone is 0.1 to 0.12 MPa; the solid content of the underflow of the hydroclone is 600-800 g/l; and the solid content of the overflow of the hydroclone is 100-150 g/1; (2) The subsequent normal pressure desilication procedure: the desilication solid content is 600-800 g/1; the desilication temperature is 100-105 °C; and desilication time is 8-12 hours- Hydroclone is standard equipment widely used in this industry, which takes small area of land and is relatively cheap and, as a result, the addition of investment is not great. Since the solid content of the raw slurry is increased, the flow rate of raw slurry sent to the desilication procedure is reduced by large amount. Therefore, the number of the normal pressure desilication tanks can be reduced properly so as to save investment in normal pressure desilication procedure. The new process has the following characteristics. Firstly, it is possible to increase the solid content of the raw slurry by times, which is favorable to increase of the desilication rate of the raw sluny. Secondly the solid content of the raw slurry is increased from 250 to 300 g/1 to more than 600g/l while the flow rate is reduced by about 50%, which can reduce the number of the normal pressure desilication tanks by large amount. Taking a digesting workshop with an output of 400 kt/a of alumina as an example, 8 stirring tanks of O10x16 m are provided for normal pressure desilication, wherein 2 heating tanks, 5 desilication tanks, and 1 common spare tank. After this invention is adopted, the number of the desilication tanks can be reduced to 3. Considering the heating tanks and the common spare tank, only 6 stirring tanks of 10x16 m in this procedure can satisfy the requirement, which can saves 2 desilication tanks. It is estimated that the investment in engineering can be saved by more than 4,000,000 Yuan. The beneficial effect of this invention is: capable of efficiently increasing the solid content of raw slurry, improving the technical indexes of the desilication procedure, and saving engineering investment. Description of Figures Figure 1 is a schematic flow chart of this inventive process. Mode of Carrying out the Invention Embodiment 1 of this invention: A hydroclone concentration equipment is provided in the procedure after grading by a hydroclone, the specification of the hydroclone is  300--500; the raw slurry from the grading overflow port of the hydroclone in the present raw milling procedure has a soiid content of 250 to 300 g/1 and a pressure of 0.1 to 0.12 MPa and is sent to the added hydroclone for concentration; the underflow raw slurry after the concentrating has a solid content of up to 600 to 800 g/1 and is sent as a product of this procedure to the normal pressure desilication procedure; and the overflow after the concentrating by the hydroclone has a solid content of 100 to 150 g/1 and is returned to an intermediate pump tank for cycle grading and concentrating. Since the solid content of the raw slurry is increased by large amount, the number of the normal pressure desilication tanks can be reduced properly. Embodiment 2 of this invention: The overflow product of the raw slurry obtained from the present hydroclone grading set (or the helical grader) In the alumina factory has a solid content of 200 to 300 g/1 and enters an intermediate raw slurry tank; the material within the intermediate raw slurry tank is sent by a pump and a pipeline to one or more (set of) added hydroclone concentration equipment (The numbers thereof are determined based on the production scale.), wherein the feeding pressure of the hydroclone concentration equipment is 0.1 to 0.12 MPa, the specification of the hydroclone is 300-500; the underflow raw slurry has a solid content of up to 600 to 800 g/1 after the concentrating and is sent as a product of this procedure to the normal pressure desilication procedure; and the overflow has a solid content of 100 to 150 g/1 after the concentrating by the hydroclone and is returned to the intermediate pump tank for cycle grading and concentrating. Claims 1. A process for increasing solid content of raw slurry, characterized in that a raw slurry concentration establishment is added behind a hydrocyclone grading procedure on the basis of the conventional process, wherein the process includes: the raw slurry from the grading overflow port of the hydrocione in the present raw milling procedure, which has a solid content of 250 to 300g/l, is sent to the added hydrocione for concentration; the concentrated underflow raw slurry has a solid content of up to 600 to 800g/l and is sent as a product of this procedure to the normal pressure desilication procedure; and the concentrated overflow from the hydrocione is returned to the intermediate pump tank for cycle grading and concentrating. 2. The process for increasing solid content of raw slurry according to claim 1, characterized in that the raw slurry concentration establishment adopts the concentration manner of using a hydrocione, and the specification of the hydrocione is 300 to 500. 3. The process for increasing solid content of raw slurry according to claim 1, characterized in that the solid content of the feed of the hydrocione is 250 to 300g/l; the pressure of the feed of the hydrocione is 0.1 to 0.12 MPa; the solid content of the underflow of the hydrocione is 600-800g/l; and the solid content of the overflow of the hydrocione is 100-150g/i; the desilication solid content is 600-800 g/1; the

Full Text

Process for Increasing Solid Content of Raw Slurry
Technical Field
This invention relates to an alumina production process for use in the raw material grinding procedure in alumina factories.
Background Art
In the raw material grinding procedure in alumina factories using Bayer process, bauxite, lime, and a part of recycling spent liquor are fed together into a raw mill in a certain proportion for grinding. The slurry after the grinding is graded by means of a hydroclone or a spiral grader The graded underflow is returned to the raw mill for fine grinding again. The graded overflow is sent as raw slurry to the normal pressure desilication procedure in a digesting workshop for normal pressure desilication.
Suppose a hydroclone is used for grading of raw slurry, the solid content into the hydrocyclone is 400 to 550g/l; the solid content of the underflow of the hydrocyclone is 800 to lOOOg/1; and the solid content of the overflow is 250-300 g/1. The solid content index of the subsequent normal pressure desilication procedure is affected by the solid content of the overflow of the hydrocyclone of the raw mill and thus cannot be improved by the present procedure.
The main technical indexes in the normal pressure desilication procedure in production at present include; desilication solid content is around 300g/l; the desilication temperature is 100 to 105°C; and the desilication time is 8 to 12 hours. Spoken from process, solid content is one of the important indexes that affect the desilication effect of aluminum ores. The results of the processing performance tests for bauxites at various regions show that the desilication solid content is proportional to the desilication rate of bauxites. The higher the solid content is, the higher the desilication rate is, and the better the effect of the normal pressure desilication effect is. The desilication solid content that is generally recommended by the test report is 600 to 800g/l.

The present raw milling procedure is affected by the grader, and the solid content of the raw slurry at present can only reach to 250 to 300 g/1, which cannot meet the requirement of 600 to 800 g/1 recommended in the test report.
Summary of the Invention
The object of this invention is to raise a process for increasing the solid content of raw slurry, which uses a new concentration process by a hydroclone to increase the solid content of raw slurry sent to the normal pressure desilication procedure to 600 to 800 g/1 to increase the desilication efficiency of the raw slurry while reduce the investment in normal pressure desilication procedure.
This invention is thus realized: a raw slurry concentrating equipment is added behind a hydrocyclone grading procedure on the basis of the conventional process, wherein the process includes: the raw slurry from the grading overflow port of the hydroclone in the present raw milling procedure, which has a solid content of 250 to 300g/l3 is sent to the added hydroclone for concentration; the concentrated underflow raw slurry has a solid content of up to 600 to 800g/l and is sent as a product of this procedure to the normal pressure desilication procedure; and the concentrated overflow from the hydroclone is returned to the intermediate pump tank for cycle grading and concentrating.
The raw slurry concentration establishment adopts the concentration manner of using a hydroclone. The specification of the hydroclone is 300 to 500.
The foregoing process has the following main technical indexes:
(1) The hydroclone concentration procedure: the solid content of the feed of the hydroclone is 250 to 300 g/1; the pressure of the feed of the hydroclone is 0.1 to 0.12 MPa; the solid content of the underflow of the hydroclone is 600-800 g/l; and the solid content of the overflow of the hydroclone is 100-150 g/1;
(2) The subsequent normal pressure desilication procedure: the desilication solid content is 600-800 g/1; the desilication temperature is 100-105 °C; and desilication time is 8-12 hours-
Hydroclone is standard equipment widely used in this industry, which takes

small area of land and is relatively cheap and, as a result, the addition of investment is not great. Since the solid content of the raw slurry is increased, the flow rate of raw slurry sent to the desilication procedure is reduced by large amount. Therefore, the number of the normal pressure desilication tanks can be reduced properly so as to save investment in normal pressure desilication procedure.
The new process has the following characteristics. Firstly, it is possible to increase the solid content of the raw slurry by times, which is favorable to increase of the desilication rate of the raw sluny. Secondly the solid content of the raw slurry is increased from 250 to 300 g/1 to more than 600g/l while the flow rate is reduced by about 50%, which can reduce the number of the normal pressure desilication tanks by large amount. Taking a digesting workshop with an output of 400 kt/a of alumina as an example, 8 stirring tanks of O10x16 m are provided for normal pressure desilication, wherein 2 heating tanks, 5 desilication tanks, and 1 common spare tank. After this invention is adopted, the number of the desilication tanks can be reduced to 3. Considering the heating tanks and the common spare tank, only 6 stirring tanks of 10x16 m in this procedure can satisfy the requirement, which can saves 2 desilication tanks. It is estimated that the investment in engineering can be saved by more than 4,000,000 Yuan.
The beneficial effect of this invention is: capable of efficiently increasing the solid content of raw slurry, improving the technical indexes of the desilication procedure, and saving engineering investment.
Description of Figures
Figure 1 is a schematic flow chart of this inventive process.
Mode of Carrying out the Invention
Embodiment 1 of this invention:
A hydroclone concentration equipment is provided in the procedure after grading by a hydroclone, the specification of the hydroclone is  300--500; the raw slurry from the grading overflow port of the hydroclone in the present raw milling procedure

has a soiid content of 250 to 300 g/1 and a pressure of 0.1 to 0.12 MPa and is sent to the added hydroclone for concentration; the underflow raw slurry after the concentrating has a solid content of up to 600 to 800 g/1 and is sent as a product of this procedure to the normal pressure desilication procedure; and the overflow after the concentrating by the hydroclone has a solid content of 100 to 150 g/1 and is returned to an intermediate pump tank for cycle grading and concentrating. Since the solid content of the raw slurry is increased by large amount, the number of the normal pressure desilication tanks can be reduced properly.
Embodiment 2 of this invention:
The overflow product of the raw slurry obtained from the present hydroclone grading set (or the helical grader) In the alumina factory has a solid content of 200 to 300 g/1 and enters an intermediate raw slurry tank; the material within the intermediate raw slurry tank is sent by a pump and a pipeline to one or more (set of) added hydroclone concentration equipment (The numbers thereof are determined based on the production scale.), wherein the feeding pressure of the hydroclone concentration equipment is 0.1 to 0.12 MPa, the specification of the hydroclone is 300-500; the underflow raw slurry has a solid content of up to 600 to 800 g/1 after the concentrating and is sent as a product of this procedure to the normal pressure desilication procedure; and the overflow has a solid content of 100 to 150 g/1 after the concentrating by the hydroclone and is returned to the intermediate pump tank for cycle grading and concentrating.

Claims
1. A process for increasing solid content of raw slurry, characterized in that a raw
slurry concentration establishment is added behind a hydrocyclone grading procedure
on the basis of the conventional process, wherein the process includes: the raw slurry
from the grading overflow port of the hydrocione in the present raw milling procedure,
which has a solid content of 250 to 300g/l, is sent to the added hydrocione for
concentration; the concentrated underflow raw slurry has a solid content of up to 600
to 800g/l and is sent as a product of this procedure to the normal pressure desilication
procedure; and the concentrated overflow from the hydrocione is returned to the
intermediate pump tank for cycle grading and concentrating.
2. The process for increasing solid content of raw slurry according to claim 1,
characterized in that the raw slurry concentration establishment adopts the
concentration manner of using a hydrocione, and the specification of the hydrocione
is 300 to 500.
3. The process for increasing solid content of raw slurry according to claim 1,
characterized in that the solid content of the feed of the hydrocione is 250 to 300g/l;
the pressure of the feed of the hydrocione is 0.1 to 0.12 MPa; the solid content of the
underflow of the hydrocione is 600-800g/l; and the solid content of the overflow of
the hydrocione is 100-150g/i; the desilication solid content is 600-800 g/1; the

Documents:

271 CHENP 2008 Petition for verification of the PCT application.pdf

271-CHENP-2008 AMENDED CLAIMS 27-05-2014.pdf

271-CHENP-2008 AMENDED PAGES OF SPECIFICATION 27-05-2014.pdf

271-CHENP-2008 AMENDED CLAIMS 31-10-2014.pdf

271-CHENP-2008 CORRESPONDENCE OTHERS 15-09-2014.pdf

271-CHENP-2008 CORRESPONDENCE OTHERS 12-08-2014.pdf

271-CHENP-2008 CORRESPONDENCE OTHERS 18-06-2014.pdf

271-CHENP-2008 CORRESPONDENCE OTHERS 18-11-2013.pdf

271-CHENP-2008 ENGLISH TRANSLATION 27-05-2014.pdf

271-CHENP-2008 EXAMINATION REPORT REPLY RECEIVED 27-05-2014.pdf

271-CHENP-2008 FORM-3 27-05-2014.pdf

271-CHENP-2008 OTHER PATENT DOCUMENT 12-08-2014.pdf

271-CHENP-2008 CORRESPONDENCE OTHERS 07-10-2014.pdf

271-CHENP-2008 CORRESPONDENCE OTHERS 27-02-2014.pdf

271-CHENP-2008 EXAMINATION REPORT REPLY RECEIVED 31-10-2014.pdf

271-CHENP-2008 FORM-1 27-02-2014.pdf

271-CHENP-2008 OTHER PATENT DOCUMENT 27-02-2014.pdf

271-CHENP-2008 POWER OF ATTORNEY 31-10-2014.pdf

271-chenp-2008-abstract.pdf

271-chenp-2008-claims.pdf

271-chenp-2008-correspondnece-others.pdf

271-chenp-2008-description(complete).pdf

271-chenp-2008-drawings.pdf

271-chenp-2008-form 1.pdf

271-chenp-2008-form 26.pdf

271-chenp-2008-form 3.pdf

271-chenp-2008-form 5.pdf

271-chenp-2008-pct.pdf

726-2008_Petition 137.pdf

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Patent Number

263981

Indian Patent Application Number

271/CHENP/2008

PG Journal Number

49/2014

Publication Date

05-Dec-2014

Grant Date

28-Nov-2014

Date of Filing

17-Jan-2008

Name of Patentee

CHINA ALUMINUM INTERNATIONAL ENGINEERING CORPORATION LIMITED

Applicant Address

B-15/F, TONGTAI MANSION, 33 JINRONG STREET, XICHENG DISTRICT, BEIJING 100032, CHINA.

Inventors:

#	Inventor's Name	Inventor's Address
1	CHEN, DE	208 BEIJING ROAD, GUIYANG CITY, GUIZHOU PROVINCE 550004, CHINA.

PCT International Classification Number

C01F 7/02

PCT International Application Number

PCT/CN2006/001742

PCT International Filing date

2006-07-18

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	200510200403.1	2005-07-18	China