CA1207641A - Recovery and recycle of nitrate and nitrite salts from chloride containing quench bath solids - Google Patents
Recovery and recycle of nitrate and nitrite salts from chloride containing quench bath solidsInfo
- Publication number
- CA1207641A CA1207641A CA000426868A CA426868A CA1207641A CA 1207641 A CA1207641 A CA 1207641A CA 000426868 A CA000426868 A CA 000426868A CA 426868 A CA426868 A CA 426868A CA 1207641 A CA1207641 A CA 1207641A
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- solids
- weight
- process according
- nitrate
- leaching
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Abstract
RECOVERY AND RECYCLE OF NITRATE
AND NITRITE SALTS FROM CHLORIDE
CONTAINING QUENCH BATH SOLIDS
Abstract A method is provided for the recovery and recycle of nitrate and nitrite salts present in environmentally hazardous chloride containing quench bath solids, com-prising the steps of leaching the solids with hot water o provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the re-sulting aqueous leachate of solids, and recycling it while hot into a fused quench bath.
AND NITRITE SALTS FROM CHLORIDE
CONTAINING QUENCH BATH SOLIDS
Abstract A method is provided for the recovery and recycle of nitrate and nitrite salts present in environmentally hazardous chloride containing quench bath solids, com-prising the steps of leaching the solids with hot water o provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the re-sulting aqueous leachate of solids, and recycling it while hot into a fused quench bath.
Description
P RK - 15 4 ~ r~
Description RECOVERY AND RECYCLE OF NITRATE
AND NITRITE SALTS FROM CHLORIDE
CONTAI~;IING QUEWC~I BATH SOLIDS
Technical Field This invention relates to a method for the recovery and recycle of nitrate and nitrite salts present in environmentally hazardous chloride con~
taining quench bath solids. In particular, the inven-tion relates to a method comprising the steps of leachingthe quench bath solids with hot water to provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the resulting aqueous leachate of solids, and recycling it while hot into a fused quench bath.
Background Art Commercial hardening techniques for ferxous metal obYects or workpieces typically involve sequencing the objects batchwise through a high heat treatment, a quench, and one or more rinses. In particularl these involve heating the objects in a high heat (e.g., 1500-1700 F.) bath of neutral molten salt such as chloride (especially NaCl and KCl), and ~uenching the heated objects in another, less hot (e.g.~ 350-700F.) molten agitated isothermal salt bath or quench bath, such as a bath o~
nitrate and nitrite salts, e~g., a mixture of sodium nitrate, potassium nitrate and sodium nitrite salts.
Thus, a certain amount of the chloride salt is txans-ferred on each object by drag-out from the high heat bath ..?~?~. --PRK-15~ ~Z~37~4 1 ~o the quench bath; for a description of a similar drag-out into rinse water, see U.S. 4,158,579. The chloride salt which is dragged out is soluble in nitrate salt in amounts that are below the chloride saturation point.
As the latter point is reached, however, further amounts of chloride salt dragged into the quench bath will fail to dissolve and will start to precipitate as a solid.
This extra salt cannot be absorbed by the bath salts and will be left in suspension or will form as sludge or solidified salt in the bath. Sludge buildup or solidified salt must be removed from the bath since it adversely affects quenching activity and efficiency.
For example, whereas 4% by weight of sodium-potas~ium chloride salts in a given nitrate-nitrite salt bath equates with saturation at a temperature of 400~F., a content of 24% chloride salts for the same bath that is saturated and solid free can exist only at temperatures above 800F. Sludge and solid removal from the bath may be accomplished manually by scrapers, ladles and the like or automatically by filtering bath-suspencled solids under agitation through fine screen baskets which when about half full of solids, are periodically removed, drained, emptied, and reinstalled. The thus discarded solids constitute an economic loss since they contain potentially valuable nitrates~ yet by reason of their high nitrate and nitrite content, the solids ~especially if disposed of with combustible waste) are regarded as fire-and ex-plosion-hazardous waste under Federal law (45 F.R. 33066-33588, Resource Conservation and Recovery Act). Treatment, storage, and disposal of the hazardous waste therefore dictate adherence, at substantial added cost, to specially prescribed safety standards. A further aspect of the stoxage and handling problem is that the waste solids when first removed from the bath are pourable but, when cooled, quickly set up into hard, rock-like masses that are difficult to break up and convert to smaller, manageable particulates.
It is therefore an object of the present inven-tion to provide means for efficient recovery and recycle P~K-154 of quench bath waste solids and sludges.
I-t is a further object of -the invention -to re-cover the nitrate and nitrite val.ues from quench bath waste solids.
It is another object to avoid the high cost of trea-tment, storage, and disposal of hazardous quench bath waste solids.
It is still another object to convert rock-like quench bath solids to a fr.iable substance that can be easily crushed and disposed of in an environmentally safe liquld or solid form.
These and other objects, features, and advan-tages of the invention will be realized from following detailed description of the invention.
Summary and Detailed Description The invention in one aspect provides a process for the recovery and recycle o nitxate and nitrite salts present in chloride containing quench bath solids, comprising the steps of leaching the solids with hot water under conditions such as to provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the resulting aqueous leachate of residual or leached solids, and delivering the leachate while hot into a fused quench bath. The process serves not only to selectively recover valuable nitrate and nitrite values but also to sharpen the quench and re-store moisture to the bath in which the values are re-cycled and to convert the unwanted rock~like quench bath solids into a friablel en~ironmentally safe residual substance for economic disposal in a solid form or in a liquid form obtained by dissol~ing in wclter.
In another aspect the invention provides a process or the handling o chloride containing solids separating in a nitrate based quench ba-th, comprisin~
the steps of removing the solids from the bath, cooling and comminuting the solids, leaching the resulting solids PI~K-I5~ r~
wi-th ho-t wa-ter to obtain an aqueous leachate that raises the chloride content of the solids above about 80%
by weight, clearing the resultiny leachate of residual solids~ and recycling -the leachate while ho-t into quench bath.
The process of the invention is broadly ap-plicable for the recovery and recycle of nitrate and nitrite salts present in chloride containing nitrate based quench bath solids. The term "chloride containing nitrate based quench bath solids" as used herein means solids or sludges obtained by recovering and cooling the solids, in any suitable way, from one or more chlorlde contaminated nitrate based (that is, nitrate, nitrite, or nitrate-nitrite based) fused quench baths.
An illustrative example of such a bath is a contaminated quench bath based on sodium and potassium nitrates and sodium nitrite and/or potassium nitrite. The manner oE
desludging and cooling is conventional and does not form a part of the invention. The leaching step is subject to wide varia-tion in conditions relative to type of equipment used, water/solids ratio, solids particle size, water temperature, leaching time, and extent of agitation of the leaching mixture. For leaching~ one may conveniently use a single-batch capacity tank, pre-ferably inox steel, or glass or inert plastic lined,equipped with a heater, an agitator, and filter outlet leading to an optional holding tank (with heating means) and delivery line adapted to recycle hot leach water at controlled rate for the replenishment of nitrate and nitrite sal-ts to one or more operating fused quench baths. The leaching water is suitably employed in the amount of at least about 0.3 part by weight of water per part of solids under conditions such that the nitrate and nitrite content presen-t in the solids is depleted below about 20% by weight or in other words the chloride salt content is raised above about 30% by weightO The latter solids, thus depleted of nitrate and nitrite con-P~ L5~
7~
-tent below -the mentioned conten-t, are deemed -to be en-vironmen-tally safe for disposal by conventional methods.
The leaching wa-ter in one preferred embodimen-t is employed in an amoun-t ranging from about 0.3 to abou-t 0.8 and more preferably about 0.4 to abou-t 0.5 part by weight for each part by weight of solids processed. ~ater can be used in excess and the leach kept boiling under e~apora-tion until the proper water solids ra-tio is achieved.
The endpoint can be determined by suitable means such as a hygrometer. Hot water, that is water at about 120F.
temperature, preferably at least 180F. and for best results at or near the boiling point (which typically may be about 220F.) of the leach mixture, is used for leaching. The solids or particulates, for purposes of leaching, should be about one inch in dimension or finer, obtained if necessary by breaking, crushing, triturating, or grinding larger masses or particulates, in any suitable way. Leaching is usually continued until a substantially steady state solution or endpoint is achieved, which typically may require about one hour. Clearing of the leacha-te from residual solids can be accomplished in any suitable way such as by sedimentation or Eiltering. Fil-tering under vacuum or under pressure is preferred. Agi-ta-tion of t~ leaching mixture may be conveniently provided by air bubbler, propeller means or mixer blades or other suitable means affording efEicient liquid-solid contact.
The clariEied leachate, free of residual solids, is recycled r while hot or equivalently after first cooling and then reheating, to the quench bath in any suitable way. For the purpose, the leachate is recycled, through a nozzle or other suitable means, to a vortex or point of good agitation in the Eused bath at a rate such -that water concentration and uniformity of quench severity are main-tained yet without undue spraying or spla-ttering of the water and sal~. Recycling sufficient to give abou-t 1/2 ~o 2% water at 400F. bath temperture is recommended (1/2 to 1% at 500 F., 1/4 to 1/2% at 600F., 1~4% at 700F ) Pr~K- I 5~1 -6- ~ ~O~
The lnvention and the manner and best means of practicing the same are illustrated by the following examples.
Example 1:
A l-KgO batch of chloride~ containing nitrate based waste quench bath solids, in chunk form about 3/4 inch or finer, obtained by desludging, cooling, and grinding, having the ~ollowing sample compositiono Component grams sodium chloride 1.84.4 potassium chloride 174~0 sodium nitrate 85.8 potassium nitrate 354.5 sodim nitrite 201.3 and 524 g. of water were charged to a 3500~cc. glass con-tainer with stainless metal cover to condense and re-cover steam. The mixture was boiled with ambient convec-tive mixing at 240F. (for about one hour) until the water content was reduced to 474 g. The mix was vacuum filtered using a large Buchner funnel and No. 41 filter paper. The content of the filtrate and residual solids (residue) analyzed respectively as follows-Content, Grams FiltrateResidue 25 Sodium chloride ---- 184.4 Potassium chloride 155.1 18.9 Sodium nitrate 79.2 6.6 Potassium nitrate 338.0 16.5 Sodium nitrite 191.4 9.9 The recovery of nitrate and nitrite salts from the wastesolids when, as specified above, the filtrate is recycled while hot to the quench bath is the following:
Component Recovery Sodium ni-trate 90gO
Potassium nitrate 95%
Sodium nitrite 95%
Prior to processing, the waste solids were classified as hazardous waste, were rock-like and dif-ficult to crush, and contained by weigh~ 35.8% chloride salts and 64.2% nitrate and nitrite salts. sy contrast, PRK-~-5~
the residual solids obtained by the described process were surprislngly qui-te friable or crushable even by hand (being measurably superior to untreated was-te solids in this respec-t) and were environmentally safe for dls-posal either ~s solid waste or in solution as drainableliquid waste. The residual solids contained 86% chloride salts and 14~ nitrate and nitrites. These results there-fore demonstra-te that the instant method is surprisingly effective at low cost for recovering and recyclin~J
valuable nitrate and nitrite salt values for quench bath purposes and for converting unwanted hazardous waste solids to safe substances which can be disposed of economically by conventional means.
Addi~ional runs using the procedure of Example 1 and illustrating recovery from other waste solid materials and conditions of operation are summarized as follows:
5~
Ul Z OI Z GI 6'Z 8-68 6'51 II uoF~FsoduIo;
8'0Z 8'0Z 8'LI L-6Z 8'11 I uoF~Fsodl3IO~*
Zo~ o,~ Eo~
FaM ~a %
~uauoduIo~
6'L8 1 05 ,~ . S~ 0 .. 01 9'~6 Z-6Z ~ oO8Z OL-O I uoF~Fsod~o~ '6 9'98 S'l .. .. .. 1-0 .. '8 Z'56 O ZZ ., - ., Z~'0 ., 'L
9'Z6 L-SI .. - - ZS-O II uoF~Fsod~
6'58 9'5 - - .. 5~'0 i- '5 -- O'L ,. . " 19-0 "
9 ' Z 8 L S 5 " .. .. Z 5 0 . 8 xallF~ s I~FU~a~ lauF~ ~
66 -6Z '-~ UF I '~oOZZ OL-O I UoF~Fsod~o~ z M) (SU~ ) auLFL azls du~ FaM ~q s~l~a) ( ~Z ~ ~1) saldun~x~
~ua~uo~ pala~o~a~ ~uF~a~l al~F~I~a hUFT~ F~I *UOF~FSO~UIO~ uau apFIo~ npFsa~ anpFsa~ spFlos~la~?M PFIS a~S~M-~lddnS
PRK-15~
These results show tha-t the process of the inven-tion serves eEfectively for the recovery and recycle of nitra-te and nitrite salt values from different types of hazardous waste quench bath solids con-~ainin~ relatively high percentages of such sal-t values. The results also show that -the residual solids obtained are environmentally safe for disposal by conventional solid and liquid waste disposal techniques.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows~
Description RECOVERY AND RECYCLE OF NITRATE
AND NITRITE SALTS FROM CHLORIDE
CONTAI~;IING QUEWC~I BATH SOLIDS
Technical Field This invention relates to a method for the recovery and recycle of nitrate and nitrite salts present in environmentally hazardous chloride con~
taining quench bath solids. In particular, the inven-tion relates to a method comprising the steps of leachingthe quench bath solids with hot water to provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the resulting aqueous leachate of solids, and recycling it while hot into a fused quench bath.
Background Art Commercial hardening techniques for ferxous metal obYects or workpieces typically involve sequencing the objects batchwise through a high heat treatment, a quench, and one or more rinses. In particularl these involve heating the objects in a high heat (e.g., 1500-1700 F.) bath of neutral molten salt such as chloride (especially NaCl and KCl), and ~uenching the heated objects in another, less hot (e.g.~ 350-700F.) molten agitated isothermal salt bath or quench bath, such as a bath o~
nitrate and nitrite salts, e~g., a mixture of sodium nitrate, potassium nitrate and sodium nitrite salts.
Thus, a certain amount of the chloride salt is txans-ferred on each object by drag-out from the high heat bath ..?~?~. --PRK-15~ ~Z~37~4 1 ~o the quench bath; for a description of a similar drag-out into rinse water, see U.S. 4,158,579. The chloride salt which is dragged out is soluble in nitrate salt in amounts that are below the chloride saturation point.
As the latter point is reached, however, further amounts of chloride salt dragged into the quench bath will fail to dissolve and will start to precipitate as a solid.
This extra salt cannot be absorbed by the bath salts and will be left in suspension or will form as sludge or solidified salt in the bath. Sludge buildup or solidified salt must be removed from the bath since it adversely affects quenching activity and efficiency.
For example, whereas 4% by weight of sodium-potas~ium chloride salts in a given nitrate-nitrite salt bath equates with saturation at a temperature of 400~F., a content of 24% chloride salts for the same bath that is saturated and solid free can exist only at temperatures above 800F. Sludge and solid removal from the bath may be accomplished manually by scrapers, ladles and the like or automatically by filtering bath-suspencled solids under agitation through fine screen baskets which when about half full of solids, are periodically removed, drained, emptied, and reinstalled. The thus discarded solids constitute an economic loss since they contain potentially valuable nitrates~ yet by reason of their high nitrate and nitrite content, the solids ~especially if disposed of with combustible waste) are regarded as fire-and ex-plosion-hazardous waste under Federal law (45 F.R. 33066-33588, Resource Conservation and Recovery Act). Treatment, storage, and disposal of the hazardous waste therefore dictate adherence, at substantial added cost, to specially prescribed safety standards. A further aspect of the stoxage and handling problem is that the waste solids when first removed from the bath are pourable but, when cooled, quickly set up into hard, rock-like masses that are difficult to break up and convert to smaller, manageable particulates.
It is therefore an object of the present inven-tion to provide means for efficient recovery and recycle P~K-154 of quench bath waste solids and sludges.
I-t is a further object of -the invention -to re-cover the nitrate and nitrite val.ues from quench bath waste solids.
It is another object to avoid the high cost of trea-tment, storage, and disposal of hazardous quench bath waste solids.
It is still another object to convert rock-like quench bath solids to a fr.iable substance that can be easily crushed and disposed of in an environmentally safe liquld or solid form.
These and other objects, features, and advan-tages of the invention will be realized from following detailed description of the invention.
Summary and Detailed Description The invention in one aspect provides a process for the recovery and recycle o nitxate and nitrite salts present in chloride containing quench bath solids, comprising the steps of leaching the solids with hot water under conditions such as to provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the resulting aqueous leachate of residual or leached solids, and delivering the leachate while hot into a fused quench bath. The process serves not only to selectively recover valuable nitrate and nitrite values but also to sharpen the quench and re-store moisture to the bath in which the values are re-cycled and to convert the unwanted rock~like quench bath solids into a friablel en~ironmentally safe residual substance for economic disposal in a solid form or in a liquid form obtained by dissol~ing in wclter.
In another aspect the invention provides a process or the handling o chloride containing solids separating in a nitrate based quench ba-th, comprisin~
the steps of removing the solids from the bath, cooling and comminuting the solids, leaching the resulting solids PI~K-I5~ r~
wi-th ho-t wa-ter to obtain an aqueous leachate that raises the chloride content of the solids above about 80%
by weight, clearing the resultiny leachate of residual solids~ and recycling -the leachate while ho-t into quench bath.
The process of the invention is broadly ap-plicable for the recovery and recycle of nitrate and nitrite salts present in chloride containing nitrate based quench bath solids. The term "chloride containing nitrate based quench bath solids" as used herein means solids or sludges obtained by recovering and cooling the solids, in any suitable way, from one or more chlorlde contaminated nitrate based (that is, nitrate, nitrite, or nitrate-nitrite based) fused quench baths.
An illustrative example of such a bath is a contaminated quench bath based on sodium and potassium nitrates and sodium nitrite and/or potassium nitrite. The manner oE
desludging and cooling is conventional and does not form a part of the invention. The leaching step is subject to wide varia-tion in conditions relative to type of equipment used, water/solids ratio, solids particle size, water temperature, leaching time, and extent of agitation of the leaching mixture. For leaching~ one may conveniently use a single-batch capacity tank, pre-ferably inox steel, or glass or inert plastic lined,equipped with a heater, an agitator, and filter outlet leading to an optional holding tank (with heating means) and delivery line adapted to recycle hot leach water at controlled rate for the replenishment of nitrate and nitrite sal-ts to one or more operating fused quench baths. The leaching water is suitably employed in the amount of at least about 0.3 part by weight of water per part of solids under conditions such that the nitrate and nitrite content presen-t in the solids is depleted below about 20% by weight or in other words the chloride salt content is raised above about 30% by weightO The latter solids, thus depleted of nitrate and nitrite con-P~ L5~
7~
-tent below -the mentioned conten-t, are deemed -to be en-vironmen-tally safe for disposal by conventional methods.
The leaching wa-ter in one preferred embodimen-t is employed in an amoun-t ranging from about 0.3 to abou-t 0.8 and more preferably about 0.4 to abou-t 0.5 part by weight for each part by weight of solids processed. ~ater can be used in excess and the leach kept boiling under e~apora-tion until the proper water solids ra-tio is achieved.
The endpoint can be determined by suitable means such as a hygrometer. Hot water, that is water at about 120F.
temperature, preferably at least 180F. and for best results at or near the boiling point (which typically may be about 220F.) of the leach mixture, is used for leaching. The solids or particulates, for purposes of leaching, should be about one inch in dimension or finer, obtained if necessary by breaking, crushing, triturating, or grinding larger masses or particulates, in any suitable way. Leaching is usually continued until a substantially steady state solution or endpoint is achieved, which typically may require about one hour. Clearing of the leacha-te from residual solids can be accomplished in any suitable way such as by sedimentation or Eiltering. Fil-tering under vacuum or under pressure is preferred. Agi-ta-tion of t~ leaching mixture may be conveniently provided by air bubbler, propeller means or mixer blades or other suitable means affording efEicient liquid-solid contact.
The clariEied leachate, free of residual solids, is recycled r while hot or equivalently after first cooling and then reheating, to the quench bath in any suitable way. For the purpose, the leachate is recycled, through a nozzle or other suitable means, to a vortex or point of good agitation in the Eused bath at a rate such -that water concentration and uniformity of quench severity are main-tained yet without undue spraying or spla-ttering of the water and sal~. Recycling sufficient to give abou-t 1/2 ~o 2% water at 400F. bath temperture is recommended (1/2 to 1% at 500 F., 1/4 to 1/2% at 600F., 1~4% at 700F ) Pr~K- I 5~1 -6- ~ ~O~
The lnvention and the manner and best means of practicing the same are illustrated by the following examples.
Example 1:
A l-KgO batch of chloride~ containing nitrate based waste quench bath solids, in chunk form about 3/4 inch or finer, obtained by desludging, cooling, and grinding, having the ~ollowing sample compositiono Component grams sodium chloride 1.84.4 potassium chloride 174~0 sodium nitrate 85.8 potassium nitrate 354.5 sodim nitrite 201.3 and 524 g. of water were charged to a 3500~cc. glass con-tainer with stainless metal cover to condense and re-cover steam. The mixture was boiled with ambient convec-tive mixing at 240F. (for about one hour) until the water content was reduced to 474 g. The mix was vacuum filtered using a large Buchner funnel and No. 41 filter paper. The content of the filtrate and residual solids (residue) analyzed respectively as follows-Content, Grams FiltrateResidue 25 Sodium chloride ---- 184.4 Potassium chloride 155.1 18.9 Sodium nitrate 79.2 6.6 Potassium nitrate 338.0 16.5 Sodium nitrite 191.4 9.9 The recovery of nitrate and nitrite salts from the wastesolids when, as specified above, the filtrate is recycled while hot to the quench bath is the following:
Component Recovery Sodium ni-trate 90gO
Potassium nitrate 95%
Sodium nitrite 95%
Prior to processing, the waste solids were classified as hazardous waste, were rock-like and dif-ficult to crush, and contained by weigh~ 35.8% chloride salts and 64.2% nitrate and nitrite salts. sy contrast, PRK-~-5~
the residual solids obtained by the described process were surprislngly qui-te friable or crushable even by hand (being measurably superior to untreated was-te solids in this respec-t) and were environmentally safe for dls-posal either ~s solid waste or in solution as drainableliquid waste. The residual solids contained 86% chloride salts and 14~ nitrate and nitrites. These results there-fore demonstra-te that the instant method is surprisingly effective at low cost for recovering and recyclin~J
valuable nitrate and nitrite salt values for quench bath purposes and for converting unwanted hazardous waste solids to safe substances which can be disposed of economically by conventional means.
Addi~ional runs using the procedure of Example 1 and illustrating recovery from other waste solid materials and conditions of operation are summarized as follows:
5~
Ul Z OI Z GI 6'Z 8-68 6'51 II uoF~FsoduIo;
8'0Z 8'0Z 8'LI L-6Z 8'11 I uoF~Fsodl3IO~*
Zo~ o,~ Eo~
FaM ~a %
~uauoduIo~
6'L8 1 05 ,~ . S~ 0 .. 01 9'~6 Z-6Z ~ oO8Z OL-O I uoF~Fsod~o~ '6 9'98 S'l .. .. .. 1-0 .. '8 Z'56 O ZZ ., - ., Z~'0 ., 'L
9'Z6 L-SI .. - - ZS-O II uoF~Fsod~
6'58 9'5 - - .. 5~'0 i- '5 -- O'L ,. . " 19-0 "
9 ' Z 8 L S 5 " .. .. Z 5 0 . 8 xallF~ s I~FU~a~ lauF~ ~
66 -6Z '-~ UF I '~oOZZ OL-O I UoF~Fsod~o~ z M) (SU~ ) auLFL azls du~ FaM ~q s~l~a) ( ~Z ~ ~1) saldun~x~
~ua~uo~ pala~o~a~ ~uF~a~l al~F~I~a hUFT~ F~I *UOF~FSO~UIO~ uau apFIo~ npFsa~ anpFsa~ spFlos~la~?M PFIS a~S~M-~lddnS
PRK-15~
These results show tha-t the process of the inven-tion serves eEfectively for the recovery and recycle of nitra-te and nitrite salt values from different types of hazardous waste quench bath solids con-~ainin~ relatively high percentages of such sal-t values. The results also show that -the residual solids obtained are environmentally safe for disposal by conventional solid and liquid waste disposal techniques.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows~
Claims (15)
1. A process for the recovery and recycle of nitrate and nitrite salts present in chloride containing quench bath solids, comprising the steps of leaching the solids with hot water to provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the resulting aqueous leachate of residual solids, and delivering the leachate while hot into a fused quench bath.
2. A process according to Claim 1 where the solids are leached with hot water in the amount of at least about 0.3 part by weight of water per part by weight of solids under conditions such that the nitrate and nitrite content present in the solids is depleted below about 20% by weight.
3. A process according to Claim 2 where the leaching step is carried out at the boiling point of the leaching mixture.
4. A process according to Claim 2 where the leaching step is carried out for at least one hour.
5. A process according to Claim 2 where the partical size of the solids subjected to leaching is about one inch or finer.
6. A process according to Claim 2 where the amount of hot water is in the range from about 0.3 part to about 0.8 part per part of solids.
7. A process according to Claim 1 where the solids contain sodium chloride and potassium chloride and the solids are leached with hot water in the amount of at least about 0.3 part by weight of water per part by weight of solids under conditions such that the chloride salt content of the solids is raised above about 80% by weight.
8. A process according to Claim 7 where the leaching step is carried out at the boiling point of the leaching mixture.
9. A process according to Claim 7 where the leaching step is carried out for at least one hour.
10. A process according to Claim 7 where the particle size of the solids subjected to leaching is less than about one inch.
11. A process according to Claim 1 where the leachate is filtered while hot.
12. A process according to Claim 11 where the filtered leachate is delivered into the quench bath directly after filtering.
13. A process for the handling of chloride con-taining solids separating in a nitrate based quench bath, comprising the steps of removing the solids from the bath, cooling and comminuting the solids, leaching the re-sulting solids with hot water to obtain an aqueous leachate that raises the chloride content of the solids above about 80% by weight, clearing the resulting leachate of residual solids, and recycling the leachate while hot into a quench bath.
14. A process according to Claim 13 where the solids contain nitrate and nitrite salts and the solids are leached with hot water in the amount of at least about 0.3 part by weight of water per part by weight of solids for a time sufficient to lower the nitrate and nitrite content of the solids below 20% by weight.
15. A process according to Claim 13 where the solids contain sodium chloride and potassium chloride and the solids are leached with hot water in the amount of at least about 0.3 part by weight of water per part by weight of solids for a time sufficient to raise the sodium chloride and potassium chloride content of the solids to more than 80% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000426868A CA1207641A (en) | 1983-04-27 | 1983-04-27 | Recovery and recycle of nitrate and nitrite salts from chloride containing quench bath solids |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000426868A CA1207641A (en) | 1983-04-27 | 1983-04-27 | Recovery and recycle of nitrate and nitrite salts from chloride containing quench bath solids |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207641A true CA1207641A (en) | 1986-07-15 |
Family
ID=4125114
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000426868A Expired CA1207641A (en) | 1983-04-27 | 1983-04-27 | Recovery and recycle of nitrate and nitrite salts from chloride containing quench bath solids |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1207641A (en) |
-
1983
- 1983-04-27 CA CA000426868A patent/CA1207641A/en not_active Expired
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