IL32429A - Working of refractory magnesia bodies - Google Patents

Description

Working of refractory magnesia bodies THE STATE OP ENERGY COMMISSION Inventorst Samuel Raviv Elsa Rablnovltz 29339 The present invention concerns a method for refractory materials based on magnesium Various kinds of refractory articles based on magnesium oxide are in common In the course of the manufacture of these it becomes necessary to subject the refractor bod serving as starting material to various mechanical working such as milling and the Practice has shown that a successful carrying out of all these operations requires cumbersome equipment with special tools in view of the high abrasion and wear and have to be replaced the energetic requirements for working refractory bodies based on magnesia are Magnesia is classified as an electrically conductive magnesia is known to be insoluble in conventional such as alcohol and various It surprising to discover in accordance with the that refractory bodies based on magnesia can be worked very conveniently by an electrolytic process in a selected solvent system serving as The invention consists in a method for working a refractory body based on comprising shing an electrolytic circuit in which the electrolyte is a mixture of phosphoric isobutyl alcohol and and the electrodes are inert to the electrolyte under the operational introducing the body into the electrolyte in a mity relationship as hereinafter defined with the flowing a unidirectional electric current through the circuit thereby to about local diesolu of the maintaining the proximity relationship of the body with the cathode the desired degree of local dissolution is achieved and then drawing the body from the I the may comprise two or more cathodes connected in The term is used herein to describe distance between the body and the cathode and is meant to imply either direct physical contact or a spaced relationship not exceeding 10 The description implies dissolution within the zone is in and a voltage 20 a mixture comprising by volume of lsobutyl by volume of phosphoric acid and by volume of water will Under conditions it through is possible to of to mm about 50 minutes to produce a hole o to mm in Within the scope of the above general method many different embodiments are accordance with One a refractory magnesia body is bored by placin one or more oblong cathodes each in proximity relationship temperattires or only slightly elevated The method according to the invention differs ally from all hitherto known electrolytic known electrolytic processes the system comprises only a anode and an electrolytic Where in such a process a body has to worked an or the body itself forms one of the the In where a body is worked in accordance with a known method and thus serves an electrode in the this the changes in the course of the In distinction in the method according to the three elements are present in the electrolytic an a cathode and the body that is being The body which is thus neither cathode nor anode for reasons of its proximity ship with the be termed hereinafter as In a system according to the invention only changes in accordance with the whereas cathodes and anodes substantially It is a characteristic feature of the present vention that the treatment of the refractory magnesia body localized is and only a zone of the that in proximity relationship the cathode is whereas the remaining part of the remains It is du to feature that a complete of the possible and the may in dance with the present invention be shaped in any desired that The magnesia in accordance with locally the invention and thereb worked i a desired is rather surprising havin regard to the fac that is classified an electric It is believed that is based on local of the surface phenomena on the an modifications Occur in the of close proximity to the These phenomena due to the electrolyte and are not properties of the The invention is by of example in the accompanying which is a wiring gram of an electrolytic system for carrying out the method according the shown in the drawing an electrolytic system in accordance with the invention comprises vessel 1 holding an whose composition is as hereinbefore Into vessel 1 dips a cathode an anode 4 and mersed in the bath and positioned in proximity relationship with the tip of cathode 3 is an 5 which is the refractory magnesia body to be worked in accordance with the Cathode 3 is connected to the and 4 the positive terminal of an electric battery ur An A serves for the current intensity and a volt meter for voltage She system further comprises switching means as well as and I tensity controlling means whic are all known se and not illustrated in the Where it is for to bore hole in antircathode 5 the is switched on and the 5 and oathode 3 are gradually moved towards each other as the The Operation continues as long as desired and is interrupted by switching off the The processed is then removed from the The invention is further illustrated by the following example to which it is not through series of tests was run for mm thick based refractory The teste were all conducted in device of the kind described ploying an oblong cathode whose pointed tip ed in direction of the intended The bath temperature was The composition of the refractory material of which the plate was made was as 97 99 2 The operational conditions and results are tabulated The bores produced had a diameter of to Composition Of the Test Conditions vations Aqueous I Time ric acid 8 alcohol minutes 1 0 100 no cing 27 73 3P 135 3 40 60 20 30 4 40 60 15 40 is seen from the table that where the lyte consisted of pure isotoutyl alcohol pure no piercing of the magnesia plate On the other hand i tests 2 to 5 comprised phosphoric and water the aqueous phosphoric acid the plate was 9 insufficientOCRQuality

Claims (9)

1. A method for working a refractory body baaed on v magnesia, comprising establishing an electrolytic circuit in which the electrolyte is a mixture of phosphoric acid, isobutyl an water and the electrodes arc inert to the electrolyte under the operational conditions, introducing the body into the electrolyte in a proximity relationship as hereinbefore defined with the cathode, flowing a unidirectional electric current through the circuit thereb to bring about local dissolution of the body, maintaining the proximity relationship of the body with the Cathode until the desired degree of local dissolution is achieved and then withdrawing the body from the electrolyte.

2. · " A method according to Claim 1 , wherein at least two cathodes are applied to said body.

3. A method according to Claim 1, wherein said working operation consists in boring by placing at least one oblong cathode in proximity relationship to said body, if desired by moving the body and cathode gradually towards each other and flowing the electric current until the bore is complete.

4. A method according to Claim 1 or 2, wherein an existing bore in said body is widened by placing an oblon cathode in the bore so as to extend therethrough in axial direction and the electric current is made to flow until the bore is widened to the desired diameter.

5. A method according to Claim 1 or 2, wherein said body is cut or engraved by bringing at least one cathode into proximity relationship with said body along a predetermined line and flowing the electric current until the desired engraving is achieved. 32429/2 - 10 - \

6. A method according to Claim 5» wherein a pointed cathode is used and is moved along said line.

7. A method according to Claim 5» wherein a flexible cathode is bent along said line or part thereof,

8. A method according to Claim 7, wherein a cathode is wound on said body and is gradually tightened as the cutting proceeds;

9. Methods for working a refractory body based on magnesia as claimed in Claim 1 , substantially as described and e xempli ied mz