FreshPatents.com Logo
stats FreshPatents Stats
6 views for this patent on FreshPatents.com
2013: 3 views
2012: 3 views
Updated: April 14 2014
newTOP 200 Companies filing patents this week


    Free Services  

  • MONITOR KEYWORDS
  • Enter keywords & we'll notify you when a new patent matches your request (weekly update).

  • ORGANIZER
  • Save & organize patents so you can view them later.

  • RSS rss
  • Create custom RSS feeds. Track keywords without receiving email.

  • ARCHIVE
  • View the last few months of your Keyword emails.

  • COMPANY DIRECTORY
  • Patents sorted by company.

AdPromo(14K)

Follow us on Twitter
twitter icon@FreshPatents

Method and device for treating fluorine-containing water

last patentdownload pdfdownload imgimage previewnext patent


20120279928 patent thumbnailZoom

Method and device for treating fluorine-containing water


A high percentage of fluorine in fluorine-containing water is removed and high purity calcium fluoride is recovered when treating the fluorine-containing water by passing the same through calcium carbonate packed towers provided in series in a plurality of stages, preferably two stages. In a method including passing fluorine-containing water through calcium carbonate packed towers provided in series in a plurality of stages to remove the fluorine in the fluorine-containing water and recover calcium fluoride, the calcium carbonate towers are packed with calcium carbonate with a volume mean diameter of 30 to 150 μm. By the use of calcium carbonate granules with a volume mean diameter of 30 to 150 μm, an increase in the purity of the recovered calcium fluoride and an increase in the fluorine removal ratio can be realized with a relatively small device.
Related Terms: Calcium Fluoride

Browse recent Kurita Water Industries Ltd. patents - Tokyo, JP
Inventor: Shuhei Izawa
USPTO Applicaton #: #20120279928 - Class: 210752 (USPTO) - 11/08/12 - Class 210 
Liquid Purification Or Separation > Processes >Chemical Treatment >Plural Spaced Feedings

view organizer monitor keywords


The Patent Description & Claims data below is from USPTO Patent Application 20120279928, Method and device for treating fluorine-containing water.

last patentpdficondownload pdfimage previewnext patent

FIELD OF INVENTION

The present invention relates to a method and a device for treating fluorine-containing water, and more particularly relates to a method and a device for treating fluorine-containing water for removing fluorine highly from fluorine-containing water such as waste water containing a fluorine-based etching agent, and efficiently recovering the removed fluorine as calcium fluoride having high purity.

BACKGROUND OF INVENTION

A large amount of an etching agent which contains hydrogen fluoride or hydrogen fluoride and ammonium fluoride as main ingredients has been used in a semiconductor manufacturing process, a related process thereof, or a surface treatment process of various materials including metal materials, single crystal materials, optical materials, and the like. An etching agent which contains hydrogen fluoride as a main ingredient or an etching agent which contains hydrogen fluoride and ammonium fluoride (buffered hydrofluoric acid) as main ingredients contains high levels of fluorine as HF. Therefore, when these etching agents flow into a waste water system, waste water thereof become to contain fluorine at a high concentration. As materials treated with etching agents are washed with a large amount of cleaning water during etching process and after the process, a large amount of waste water containing low levels of fluorine is discharged from the washing process.

According to a conventional method, waste water containing high levels of fluorine and waste water containing low levels of fluorine are mixed and treated. Patent Document 1 discloses a method for treating fluorine-containing waste water wherein the waste water is fed to and passed through a reaction tower packed with granular calcium carbonate.

The method described in Patent Document 1, treatment is performed by a merry-go-round method, in which a plurality of towers packed with calcium carbonate are arranged in series. First, raw water is sequentially passed from a first tower (tower in a first stage) to the following tower(s) to remove and recover fluorine. When the fluorine concentration of the raw water flowing into the first tower and the fluorine concentration of the treated water flowed out from the first tower become almost the same, feeding raw water to the first tower is stopped, the calcium fluoride is recovered from the first tower, and the first tower is packed with fresh calcium carbonate. Then, raw water is fed to and passed through the second tower, and flows sequentially to the following tower(s) for the first tower.

Patent Document 1 describes that glanular calcium carbonate packed in each calcium carbonate packed tower has a diameter of about 0.1 to 0.5 mm, and specifically granular calcium carbonate having a diameter of 0.25 mm is used in Examples thereof.

Patent Document 2 discloses a method for removing fluorine from fluorine-containing raw water including a process of feeding the raw water to a reaction tower packed with granular calcium carbonate to remove the fluorine, wherein acid or alkali is added to the raw water based on an α-value calculated from measured values of fluorine concentration and acid concentration in the raw water.

LIST OF DOCUMENTS

Patent Document 1: Japanese Patent 3466637

Patent Document 2: Japanese Patent 2565110

The method described in Patent Document 1 has a problem that, in order to recover high purity calcium fluoride from the calcium carbonate packed towers, raw water is passed until the fluorine concentration of the raw water flowing into the tower in the first stage and the fluorine concentration of the treated water therefrom become almost the same, i.e., the fluorine removal ratio of the calcium carbonate packed tower in the first stage becomes almost zero. As a result thereof, fluorine leaks into the treated water of the calcium carbonate packed tower (reaction tower) in the second stage as illustrated in FIG. 4, so that the fluorine removal ratio becomes low. For example, in Example 1 of Patent Document 1, when the fluorine removal ratio of the first tower packed with the calcium carbonate is 0%, the fluorine removal ratio of the second tower is 72.7 to 77.6%, i.e., the fluorine removal ratio of the entire device is 72.7 to 77.6%, so that treated water of high water quality cannot be obtained.

In order to solve the above problem, it has also been designed to increase the number of the towers packed with calcium carbonate and to arrange the calcium carbonate packed towers in series in three or more stages. However, in this case, the treating device is enlarged in its scale, which is not preferable in every respect of the device cost, installation area, maintenance, and the like.

OBJECT AND

SUMMARY

OF INVENTION

It is an object of the present invention to solve the above-described problems, and provide a method and a device for treating fluorine-containing water capable of removing fluorine in fluorine-containing water efficiently and recovering high purity calcium fluoride when treating the fluorine-containing water by passing the same through plurality of, preferably two, calcium carbonate packed towers arranged in series.

The present inventors have conducted extensive research for solving the above-described problems, and have found that an increase in the purity of the recovered calcium fluoride and an increase in the fluorine removal ratio can be realized with a relatively small device by the use of calcium carbonate granules having a specific volume mean granule diameter.

The present invention has been accomplished based on such findings, and the gist thereof is described below.

A first aspect provides a method for treating fluorine-containing water including passing fluorine-containing water through calcium carbonate packed towers arranged in series in a plurality of stages to remove fluorine in the fluorine-containing water and recover calcium fluoride, in which the calcium carbonate granules packed in each tower have a volume mean diameter of 30 to 150 μm.

A second aspect provides a method for treating fluorine-containing water in which the calcium carbonate packed towers are arranged in series in two stages in the first aspect.

A third aspect provides a method for treating fluorine-containing water in which the calcium carbonate granules contain granules having a diameter of lower than 20 μm at a ratio of 15% or lower in the first or second aspect.

A fourth aspect provides a method for treating fluorine-containing water in which the fluorine-containing water is passed through the calcium carbonate packed towers at an SV of 0.1 to 5 hr−1 in any one of the first to third aspects.

A fifth aspect provides a device for treating fluorine-containing water, having a unit for treating fluorine-containing water in which calcium carbonate packed towers are provided in series in a plurality of stages, a unit for passing fluorine-containing water through the unit for treating fluorine-containing water, a unit for extracting treated water from the unit for treating fluorine-containing water, and a unit for recovering calcium fluoride from the calcium carbonate packed towers, in which the volume mean diameter of the calcium carbonate packed in the calcium carbonate packed towers is 30 to 150 μm.

A sixth aspect provides a device for treating fluorine-containing water in which the calcium carbonate packed towers of the unit for treating fluorine-containing water are arranged in series in two stages in the fifth aspect.

A seventh aspect provides a device for treating fluorine-containing water in which the calcium carbonate granules contain granules having a diameter of lower than 20 μm at a ratio of 15% or lower in the fifth or sixth aspect.

An eighth aspect provides a device for treating fluorine-containing water in which the fluorine-containing water is passed through the calcium carbonate packed towers at an SV of 0.1 to 5 hr−1 in any one of the fifth to seventh aspects.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an increase in the fluorine removal ratio and an increase in the purity of calcium fluoride can be realized with a relatively small device by the use of calcium carbonate granules having a specific volume mean diameter when passing fluorine-containing water through a plurality of calcium carbonate packed towers in series to remove the fluorine in the fluorine-containing water and recover the removed fluorine as calcium fluoride.



Download full PDF for full patent description/claims.

Advertise on FreshPatents.com - Rates & Info


You can also Monitor Keywords and Search for tracking patents relating to this Method and device for treating fluorine-containing water patent application.
###
monitor keywords



Keyword Monitor How KEYWORD MONITOR works... a FREE service from FreshPatents
1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored.
3. Each week you receive an email with patent applications related to your keywords.  
Start now! - Receive info on patent apps like Method and device for treating fluorine-containing water or other areas of interest.
###


Previous Patent Application:
Apparatus for the treatment of liquids
Next Patent Application:
Combined compact hot and ozonated cold water unit
Industry Class:
Liquid purification or separation
Thank you for viewing the Method and device for treating fluorine-containing water patent info.
- - - Apple patents, Boeing patents, Google patents, IBM patents, Jabil patents, Coca Cola patents, Motorola patents

Results in 0.56267 seconds


Other interesting Freshpatents.com categories:
Medical: Surgery Surgery(2) Surgery(3) Drug Drug(2) Prosthesis Dentistry   -g2-0.2305
     SHARE
  
           

FreshNews promo


stats Patent Info
Application #
US 20120279928 A1
Publish Date
11/08/2012
Document #
13503244
File Date
10/19/2010
USPTO Class
210752
Other USPTO Classes
210201
International Class
/
Drawings
5


Calcium Fluoride


Follow us on Twitter
twitter icon@FreshPatents