Filtering medium for fluid purification

Abstract

A filtering medium, a method for the production thereof, the use of said filtering medium and a method for reducing the content of multiple contaminants simultaneously in fluids by means of said filtering medium, wherein said filtering medium has or includes at least one of the following: a mixture (A) containing a major part of an iron-based powder and a minor part of a silver powder, an iron-silver powder alloy (B), and an iron-based porous and permeable composite containing silver (C).

1 . A filtering medium for reducing the content of contaminants in fluids, wherein said filtering medium comprises an iron-silver powder alloy,
 wherein the iron-silver powder alloy contains 0.01-5% of silver, by weight of the alloy, obtained by thermal bonding or thermal alloying atomized iron powder particles with silver powder particles, wherein atomized iron powder particles have a Fe-content of at least 90% by weight of the iron powder,   wherein the iron-silver powder alloy has an average particle size between 1 μm and 10 mm, and   wherein said contaminants are selected from the group consisting of chlorine containing compounds, nitrates, nitrites, heavy metals, toxic inorganic substances, toxic organic compounds, microorganisms and/or combinations thereof.   
     
     
         2 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy contains 0.05-1% of silver, by weight of the alloy. 
     
     
         3 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy has an average particle size between 20 μm and 5 mm. 
     
     
         4 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy has an average particle size between 45 μm and 2 mm. 
     
     
         5 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy is obtained by thermal alloying atomized iron powder particles with silver powder particles. 
     
     
         6 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy is obtained by thermal bonding atomized iron powder particles with silver powder particles. 
     
     
         7 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy have an average particle size between 40 and 150 μm;
 wherein the atomized iron powder particle have an average particles size between 10 μm and 150 μm, 
 wherein the silver powder particles are Ag powder particles with Ag-content of at least 99% by weight, 
 wherein the content of Ag is above 0.25 up to 1% by weight of the iron-silver powder alloy, and 
 wherein the iron-silver powder alloy is obtained by thermal bonding atomized iron powder particles with silver powder particles. 
 
     
     
         8 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy have an average particle size between 40 and 150 μm;
 wherein the atomized iron powder particle have an average particles size between 10 μm and 150 μm, 
 wherein the silver powder particles are Ag powder particles with Ag-content of at least 99% by weight, 
 wherein the content of Ag is above 0.1 up to 1% by weight of the iron-silver powder alloy, and 
 wherein the iron-silver powder alloy is obtained by thermal alloying atomized iron powder particles with silver powder particles. 
 
     
     
         9 . The filtering medium according to  claim 1 , wherein the iron-silver powder alloy is subjected to one or more of the following: compaction, heat treatment and sizing. 
     
     
         10 . A method for reducing the content of contaminants in fluids comprising the steps of:
 a) providing a filtering medium according to  claim 1 , and   b) bringing one or more contaminated fluid(s) in contact with the filtering medium to purify said one or more fluid(s).   
     
     
         11 . The method according to  claim 10 , further comprising removing the filtering medium from the purified one or more fluid(s). 
     
     
         12 . The method according to  claim 10 , wherein the contaminants are selected from the groups comprising:
 chlorine containing compounds, nitrates, nitrites, heavy metals, toxic inorganic substances, toxic organic compounds, microorganisms and/or combinations thereof, and wherein the purifying said one or more fluid(s) of step b) comprises reducing the content of at least one of the contaminants in the fluid.   
     
     
         13 . The method according to  claim 10 , wherein in step b) one or more contaminated fluid(s) are allowed to pass through the filtering medium. 
     
     
         14 . A method for the producing the filtering medium according to  claim 1 , comprising:
 mixing an atomized iron powder with silver powder particles, wherein the atomized iron powder has an average particle size between 10 mm and 1 μm, and an Fe-content of at least 90% by weight of the iron powder, and the silver powder particles have an Ag-content of at least 99% and a particle size between 0.1 to 125 μm, and wherein the mixture contains between 0.01-5% Ag by weight,   subjecting the mixture to a thermal bonding process at a temperature below 950° C., for a period of time between 5 minutes to 600 minutes in a reducing and/or inert atmosphere.   
     
     
         15 . The method according to  claim 14 , wherein the silver powder particles 10 have a particles size between 3 to 45 μm. 
     
     
         16 . The method according to  claim 14 , wherein the mixture contains between 0.05 and 1% Ag by weight. 
     
     
         17 . The method according to  claim 14 , wherein the temperature of the thermal bonding process is between 500° C. and 950° C. 
     
     
         18 . The method according to  claim 14  wherein the temperature of the thermal bonding process is between 600° C. and 950° C. 
     
     
         19 . A method for producing the filtering medium according to  claim 1 , comprising:
 mixing an atomized iron powder with silver powder particles, wherein the atomized iron powder has an average particle size between 10 mm and 1 μm, and an Fe-content of at least 90% by weight of the iron powder, and the silver powder particles have an Ag-content of at least 99% and a particle size between 0.1 to 125 μm, and wherein the mixture contains between 0.01-5% Ag by weight,   subjecting the mixture to a thermal alloying process at a temperature above 950° C., for a period of time between 5 minutes to 600 minutes in a reducing and/or inert atmosphere.   
     
     
         20 . The method according to  claim 19 , wherein the silver powder particles have a particle size between 3 and 60 μm. 
     
     
         21 . The method according to  claim 19 , wherein the mixture contains between 0.05 to 1% Ag by weight. 
     
     
         22 . The method according to  claim 19 , wherein the temperature of the thermal alloying process is between 950° C. and 1250° C. 
     
     
         23 . The method according to  claim 19 , wherein the temperature of the thermal alloying process is between 950° C. and 1200° C.