Manufacture of a Soderberg electrode incorporating a high carbon-contributing phenolic sacrificial binder
AssigneeBorden, Inc.
InventorPitchaiya Chandramouli
Life of this patent
Estimating the term…
Abstract
The invention is a novel Soderberg electrode paste composition. The composition is a mixture comprising carbonaceous aggregate, novolac resin binder, plasticizer and optionally hexamethylenetetramine. The novolac resin of the binder has a melting point of at least 100.degree. C. and a free phenol content of not more than 4% by weight based on the weight of novolac resin solids. The residual coking value of the composition of the invention is at least as great as the minimum preferred coking value of traditional Soderberg pastes which are based on coal tar pitch binder.
Claims53
A feedstock composition for the production of a Soderberg continuous carbon electrode wherein said composition has sufficient mobility to travel through the Soderberg temperature gradient as a moving viscous bed and wherein said moving viscous bed of heated composition enters a use zone of said Soderberg electrode as a paste, hardens, and attains electrode integrity, comprising
- a mixture of particulate carbonaceous aggregate, phenolic resin binder, plasticizer, and hexamethylenetetramine wherein said plasticizer has a boiling point above 200.degree. C., wherein the amount of said plasticizer is greater than 0%-50% by weight based on the combined weight of resin solids and plasticizer;
- and wherein the amount of said hexamethylenetetramine is from 0% to no more than 5% by weight based on phenolic resin solids, said mixture retaining a plasticity at 200.degree. C.,
- said phenolic resin binder comprising a phenolic novalac resin characterized by a minimum melt point of 100.degree. C. and a free phenol content of not more than 4% by weight as measured by gas chromatography analysis.
A feedstock composition for the production of a Soderberg continuous carbon electrode wherein said composition has sufficient mobility to travel through the Soderberg temperature gradient as a moving viscous bed and wherein said viscous bed enters a use zone of said Soderberg electrode, retains plasticity at about 500.degree. C., hardens and attains electrode integrity comprising
- free flowing particulate resin coated, carbonaceous aggregate, plasticizer having a boiling point above 200.degree. C. wherein the amount of said plasticizer is of 0-50% based on the total weight of resin solids and plasticizer, and hexamethylene-tetramine wherein the amount of said hexamethylenetetramine is from 0% to no more than 5% based on phenolic resin solids,
- said resin coated carbonaceous aggregate being formed from a mixture comprising phenolic novolac resin and particulate carbonaceous aggregate.
A process for making a feedstock composition for a Soderberg continuous carbon electrode prepared from a particulate carbonaceous aggregate, a resin binder comprising a phenol formaldehyde novolac resin in particulate or hot melt form, and hexamethylenetetramine, said novolac having a melting point of at least 100.degree. C., a total volatiles content at 135.degree. C. and not more than 5% by weight of said resin solids including a free phenol content of not more than 4% by weight of said resin solids as measured by gas chromatography analysis, comprising:
- mixing said particulate aggregate with sufficient resin binder so that the solids of said resin comprise 6%-15% by weight of said aggregate and with 0%-5% by weight of hexamethylenetetramine based on the weight of said phenol formaldehyde novolac to coat said aggregate to produce a free flowing resin-coated aggregate material.
A process for making a feedstock composition for the production of a Soderberg continuous carbon electrode wherein said feedstock has sufficient mobility to travel through the Soderberg temperature gradient as a moving viscous bed of heated paste that retains plasticity at about 500.degree. C. and to enter a use zone of said Soderberg electrode wherein said heated moving bed of viscous paste hardens and attains electrode integrity comprising
- mixing particulate carbonaceous aggregate, curable resin binder, plasticizer having a boiling point above 200.degree. C. wherein the amount of said plasticizer is greater than 0-50% based on the combined weight of resin solids and plasticizer, and hexamethylenetetramine wherein the amount of said hexamethylenetetramine is from 0% to no more than 5% based on resin solids, until a free flowing resin-coated aggregate material is formed, wherein said curable resin binder comprises a novolac resin in an amount of from about 5% to about 20% by weight of resin solids based on the weight of said carbonaceous aggregate, said plasticizer and said curing agent if used being present in amounts sufficient to impart sufficient mobility and flowability to said paste as it travels toward said use zone.
A process for making a Soderberg electrode comprising the steps of
- (1) passing a feedstock that retains plasticity above 200.degree. C. of resin-coated carbonaceous particles through the three Soderberg electrode forming zones wherein in a first zone said feedstock moves downwardly toward a baking zone in the form of discrete, free-flowing particles;
- (2) in said baking zone passing said feedstock through a temperature gradient and converting said feedstock from discrete free-flowing particles to a bed of a viscous paste that moves downwardly toward an electrode-forming and use zone;
- and
- (3) in said electrode-forming and use zone hardening said paste into a continuous electrode shape and then using said shape as a continuously-formed Soderberg electrode;
- wherein said feedstock comprises an admixture of resin coated carbonaceous aggregate, plasticizer having a boiling point of at least 200.degree. C. wherein the amount of said plasticizer is greater than 0%-50% based on the total weight of resin solids and plasticizer, and hexamethylenetetramine wherein the amount of said hexamethylenetetramine is from 0% to no more than 5% based on resin solids, said resin coated carbonaceous aggregate comprising a phenolic novolac resin coated on particles of a particulate carbonaceous aggregate.
Dependencies are inferred from the claim text.