US 3723073

I'll search for this specific patent number across the requested sources.

Search Results Summary

Search transparency: My queries against USPTO and CAFC-specific sources returned no usable hits (empty result sets), and only one confirmatory third-party hit (patenthub.cn, listing the same US3723073A record). I found no evidence of any CAFC 2026 docket, ITC proceeding, or district court litigation involving patent 3,723,073. That said, an empty search result is not authoritative proof of absence — I am reporting the absence as "not found," not as a confirmed negative. The substantive information below is drawn from the full patent text you supplied (Google Patents, https://patents.google.com/patent/[US3723073](/patent/US3723073)/en, fetched 2026-09-16), which is the authoritative source here.

US Patent 3,723,073

Abstract (as published): An installation for producing electric power from heat recovered in an alumina producing installation run according to the Bayer process, in which a combination of heat exchanging means is provided for recovering the heat produced in the reaction of bauxite with a caustic alkali, and also for recovering heat from steam used in the several stages of the power-generating turboalternator which is an integral part of the power station fed by waste heat. A considerable overall efficiency is obtained, so that the electric power produced with recovered heat is a remunerative by-product.

Plain-Language Overview of the Independent Claim

Claim 1 is the sole independent claim. All of claims 2–12 depend from it (directly or indirectly).

Claim 1 — An electric power production installation with double heat recovery, combined with a Bayer-process alumina plant. The claim recites four structural elements and two recovery circuits:

1. A reactor in which bauxite is reacted hot with a caustic alkali, producing a hot mass.
2. A turbo-alternator having a steam generator.
3. An evaporating assembly in which exhausted, diluted caustic alkali is concentrated — an operation that produces and discharges hot water.
4. First heat-exchanging means — feed water for the turbo-alternator's steam generator is heated by thermal exchange with a fluid that has itself previously been passed into heat-exchange relationship with the reacted bauxite/caustic mass. The key structural point is the indirect two-step exchange: the fluid picks up heat at the reactor and gives it up to the generator feed water (the reference numerals are coil 34 in reactor 10, fluid loop, exchanger 28).
5. Second heat-exchanging means — generator feed water is heated by heat exchange with the hot water discharged by the evaporating assembly that concentrates the caustic alkali solution (exchanger 29; hot water via duct 19).

So claim 1 is a combination claim: a Bayer alumina plant (reactor + evaporator) integrated with a partial-recovery power station, where the plant's two principal waste-heat streams are both tapped to preheat boiler feed water.

Dependent-claim context (brief)

• 2: turbo-alternator has high-, medium-, and low-pressure stages.
• 3: reactor fed bauxite + caustic soda ≥30°Bé + steam; reaction mass heated to ~180–230 °C by medium-pressure extraction steam; reactor contains a coil in a closed circuit with a heat exchanger and circulating heat-exchange fluid.
• 4: the fluid is water; two tanks straddle the exchanger.
• 5: the evaporating assembly is multi-stage.
• 6: second heat exchanger uses hot water from the last evaporator stage and preceding stages.
• 7: storage tank for concentrated alkali returned to the reactor.
• 8: concentrated alkali preheated in a heat exchanger fed by medium-pressure extraction steam.
• 9: first evaporator stage fed with low-pressure extraction steam.
• 10: reacted mass cooled by the coil to not more than [100] °C — note the supplied text reads "not exceeding C." with the numeral missing (OCR loss); the specification states "not exceeding 100 C."
• 11: first heat-exchanging means in series with an LP-extraction-steam exchanger.
• 12: second heat-exchanging means in series with two or more medium/low-pressure extraction-steam exchangers.

Points of Uncertainty / Caveats

1. Assignee: The record lists an "individual" assignee only. I found no evidence of a corporate assignee (e.g., an alumina or aluminum producer). Google's disclaimer applies.
2. Prior-art references cited on the face of the patent are OCR-degraded in the supplied text. Reliably readable: US 3,497,317 (Tusche). Other cited US references appear as garbled fragments ("Buscemi 203-Dig. 20," "Scandrett 23-143," "Donaldson 23-143," "Johnson 23-143," "Robfirts 23-443") with jumbled dates — I will not reconstruct or guess those numbers, per the instruction not to auto-correct identifiers.
3. Later citations (not prior art): US4145398A (Vereinigte Aluminium-Werke AG, 1979, bauxite digestion with improved heat transfer in tubular reactors) and US4380154A (Thermacore, Inc., 1983, clean coal power system) cite this patent. A 1989 Alcan International filing (JPH05503064A) and a 2013 Siemens AG filing (DE102013219716A1) appear in the "families citing" list.
4. Litigation: No CAFC 2026 docket activity located. Given the patent's anticipated 1990 expiration, any 2026 appellate litigation over this patent would be extraordinary and would require a live controversy (e.g., a pre-expiration dispute still on appeal, or a correction/reexamination matter) — I found none, but I cannot positively rule it out from the searches performed.
5. Numbering: Per your standing rule, I have treated "3723073" literally as US 3,723,073 throughout; no correction was applied.

If you need me to dig further — e.g., pull the full prior-art citation list from the USPTO PatentCenter/Public PAIR record for application 827,869, or check whether the DE/GB/FR family members have any opposition or revocation history — tell me which jurisdiction to prioritize and I'll run targeted searches.

I'll research litigation involving US patent 3723073 across litigation-tracking sources.

The initial searches returned irrelevant results. Let me try more targeted sources.

Summary: No litigation found for US Patent 3,723,073

Based on my searches of patent litigation resources (including queries aimed at Unified Patents' litigation portal, CourtListener, and general web searches for the patent number and its inventor), I found no record of any litigation involving US Patent 3,723,073.

Details of what was and was not found

Patent identification (interpreted literally from the source data):

• US Patent No. 3,723,073
• Title: "Installation for recovering electric power, combined with an alumina manufacturing installation"
• Inventor: Francesco Ettore Conti (Milan, Italy)
• Assignee: Individual (no corporate assignee)
• Priority date: 1968-06-03 (Italy, application 17,285/68)
• Filing date: 1969-05-26
• Grant/publication date: 1973-03-27
• Legal status: Expired – Lifetime; anticipated expiration 1990-03-27

Litigation search results:

• No district court case, CAFC appeal, ITC investigation, or PTAB post-grant proceeding naming US 3,723,073 as an asserted patent was located.
• The only "proceedings" associated with the patent in the source data are:
  • Cited By (2) — later patents that cited it as prior art: US4145398A (Vereinigte Aluminium-Werke A.G., 1979) and US4380154A (Thermacore, Inc., 1983). These are citations, not litigation.
  • PTAB / IPR — none listed.

Important caveats about this conclusion

1. Searches for a bare patent number returned no on-point results. Several queries returned unrelated case law (e.g., an EagleView v. Xactware opinion) or empty result sets. I was unable to retrieve a dedicated litigation record from Unified Patents' portal or CourtListener for this specific number.
2. Strong contextual reasons to expect no litigation. This is a 1968-priority foreign-origin chemical-engineering installation patent owned by an individual inventor (not a company), in a niche process-industry field. Its term expired in 1990. Patents of this profile — individually owned, non-electronic, expired for decades — are very rarely the subject of reported infringement suits, and any such suit would predate the coverage windows of most modern litigation databases.
3. Database coverage limitations. Even if a suit had been filed in the early 1970s–1980s, it may not appear in today's electronic litigation-tracking databases, which have far better coverage of post-2000 (and especially post-2010) filings.

Bottom line

No litigation is known for US Patent 3,723,073. I cannot confirm a single plaintiff, defendant, jurisdiction, case number, filing date, or outcome, because no such case was found. I am flagging this as a genuine "no results found" conclusion rather than a definitive statement that no case ever existed — for a patent of this vintage, an exhaustive check would require archival (pre-digital) court records, which are outside what these search tools cover. If you need a definitive negative, I would recommend a manual PACER docket search and a review of Westlaw/Lexis historical archives, which I cannot access here.

I have deliberately avoided returning results for similarly numbered patents (e.g., 3,723,072, 3,723,074) per your instruction.