Deep well anodes for electrical grounding

Abstract

Two related approaches are provided to controlling the relative permeability of ground water and gases developed in deep well anodic installations. The central metallic anode is encased and protected by a semi-permeable conductive cementaceous sheath, using as the sheathing material any of a number of compositions having the desired properties of permeability and conductivity. Alternatively, a conductive but impermeable anode is used in conjunction with a semi-permeable backfill material in a bore hole of a deep well anode installation, thereby achieving the same desired ends of controlling the relative permeability of water and gases in the installation.

1 . A method for preparing a deep well anode, comprising the steps of: 
 (i) providing a mold;    (ii) aligning a ground anode in the mold for receiving a protective sheath of carbonaceous cement;    (iii) encasing the anode in the mold with a dry granular carbonaceous cement and tamping the dry mixture about the anode until fully settled and shaped;    (iv) slowly adding sufficient water to fully saturate the sheath of carbonaceous cement; and    (v) curing the carbonaceous cement to hardness.    
   
   
       2 . A composition for the preparation of an electrically conductive semi-permeable sheath for the encasement of a deep well anode, comprising a siliceous cement and an electrically conductive form of carbon, said anode sheath having a water permeability between 10 −4  and 10 −6  cm/sec.  
   
   
       3 . A composition according to  claim 2 , wherein said siliceous cement is Portland cement and the composition further comprises a minor amount of an additive effective to adjust the water permeability of the anode sheath to between 10 −4  and 10 −6  cm/sec.  
   
   
       4 . A composition according to  claim 3 , wherein said additive is a water soluble alkali metal soap of a long chain fatty acid.  
   
   
       5 . A composition according to  claim 4 , wherein said Portland cement is a Type 10 Portland Cement in a concentration of between 20 and 60% by weight and said carbon is of a particle size between 50 and 150 mesh and makes up between 80 and 40% by weight of the composition.  
   
   
       6 . A composition according to  claim 5 , wherein said additive is selected from the group consisting of alkali soaps of oleic acid, stearic acid or distilled tall oil and mixtures thereof.  
   
   
       7 . In a deep well grounding system of the kind including an anode lowered into a backfilled bore hole, the improvement of providing 
 (i) a metal conductive anode encased in a conductive composition which is substantially impermeable to water and to by-product gases developed in use of the system; and    (ii) a semi-permeable conductive backfill material to allow free venting of said by-product gases while limiting undesired migration of groundwater.    
   
   
       8 . A deep well grounding system according to  claim 7 , wherein said semi-permeable backfill material comprises a flowable granulated carbon admixed with a selected amount of Type F fly ash to adjust the water permeability of the backfill to a selected degree.  
   
   
       9 . A deep well grounding system according to  claim 8 , wherein said conductive composition comprises a granular electrically conductive form of carbon compounded with a binding/sealing agent selected from cross-linked long chain fatty acids.  
   
   
       10 . A deep well grounding system according to  claim 9 , wherein said conductive composition comprises between 50 and 90% carbon, 10 to 40% of a long chain fatty acid and 1-10% of a di- or tri-valent metal oxide or hydroxide cross-linking agent.  
   
   
       11 . A deep well grounding system according to  claim 10 , wherein said carbon in the anode composition is coke breeze.  
   
   
       12 . A deep well grounding system according to  claim 9 , wherein said backfill material comprises between 50 and 90% coke breeze and between 10 and 40% Type F fly ash.