PROCESS FOR RECOVERING PROTEINS AND FATS FROM WASTE FLESH AND THE LIKE AND APPARATUS TO IMPLEMENT THE PROCESS

Abstract: A process for recovering proteins and fats from shreds of flesh and the like characterised by: mincing the product and treating it with alkaline metabisulfite to prevent the putrefaction and to oxidize the possible sulfides; letting the product to mature in an accumulation tank; causing the disgregation of the product by mixing with concentrated sulfuric acid, thus obtaining the separation of proteins and fats from water and sucking up the sulfur dioxide in case emitted; diluting the fluid compound formed by proteins, fats and water with hot water at 50-70 DEG C thus obtaining a further fluidification of fats and at the same time neutralizing the compound with lime; submitting the neutralized compound to a continuous pressing for separating solid proteins from water and fats, and separating the fats from water by decantation.

Description: Process for recovering proteins and fats from waste flesh and the like and apparatus to implement the process The orβsβnt invention relates to a DΓOCΘSS for recovering proteins and fats from waste flesh and the like and an aooaratus to implement the process. Process and apparatus for treating substances of animal, organic origin or refluent from working organic substances are known. One of these process is described in IT-A- 1-191,331 and foresees to preliminary treate the substances with sodium bisulfite, to activate them with concentrate sul uriσ acid, to subsequently recover by pressing and filtration the precipitated proteins and not-emulsified fats coming out from the previous treatment phases, thus obtaining a watery fraction which is submitted to a sharp pH inversion with caustic soda and, then to coagulate the recovered proteins with a continuous press or a filter press- This known process proved to be apprecially innovative with respect to the prior art but at the same time offered the possibility of further improvements. In particular: - the obtained proteic by-product presents a high salt content which is an undesiderable characteristic since it may damage if the product is used as fertilizer or feed - also the waste water presents a high salt content and therefore is a pollutant by-product and the traditional depurating treatments are not adequate for its discharge, _ r> _ - tne same waste water is a pollutant for sulf tes. - there is a risk of air pollution from SO2 , - it is necessary a high consumption of reactants. - the plant is considerably complex and expensive and reαuires skilled workers for its maintenance and running, - finally the plant is not fit to an intermittent feeding of substances to be treated and therefore cannot be advantageously used in the tanning industry. According to the invention all these drawbacks are eliminated by a process for recovering proteins and fats from waste flesh and the like characterised by: - mincing the product and treating it with alkaline metabisulfite to prevent the putrefaction and to oxidize the possible sulfides, - letting the product to mature in an accumulation tank, - causing the disgregation of the product by mixing it with concentrated sulfuric acid, thus obtaining the separation of proteins and fats from water and sucking up the sulfur dioxide in case emitted, - diluting the fluid compound formed by proteins, fats and water with hot water at 50-70°C thus obtaining a further fluidification of fats and at the same time neutralizing the compound with lime. - submitting the neutralized compound to a continuous pressing for separating solid proteins from water and fats, and - separing the fats from water by decantation. The plant to implement the process according to the invention comprises: - an industrial mincer, - a distributor of alkaline metabisulfite, - an accumulation and maturing tank of the product to be treated, already minced and mixed with alkaline metabisulfite, - a reactor in which it occurs the mixing of the matured substance with concentrate sulfuric acid and subsequently with hot water and milk of lime, - sucking means for the fumes in case emitted from the reactions within the reactor, - press means for separating the products coming out from the reactor in a mostly proteic fraction and in a fraction comprising water and fats, - separing means for the water from fats and other solid wastes. The present invention is further clarified with reference to the enclosed sheets of drawings in which: - A- - Figure 1 shows schema ically a plant to implement the process according to the invention, and Figure 2 shows a block diagram of the process- As it can be seen from the drawings, the plant to implement the process according to the invention can be divided into a station 1 for mincing the substances to be treated, a station 2 for treating such substances, .and a station 3 for separating fats. More precisely the station 1 comprises an industrial mincer 4 provided with a feed chute 5 of the substances to be treated, fed through a draining belt conveyor and having its exit underlying the feed chute 6 of a Mohno pump 7 , in which also the exit duct 8 ends of a dosator 9 for sodium metabisul ite. The pump 7 communicates with an accumulation tank 10, in its turn connected to a further Hohno pump 11, which feeds two reactors 12,12' in cascade connection. These reactors 12,12' , which belong to the treatment station 2, comprise a closed cylindrical container, slightly inclined, inside which a paddle wheel screw rotates- The reactor 12 is provided, near the higher inlet side, with a feed chute 13, in which the exit pipe ends of the Mohno pump 11, and is provided near the lower exit side with a duct 14 for sucking up fumes- As already said, the two reactors 12.12' are in cascade connection. that is the exit side of the reactor 12 is overlying the h.gher inlet side of the reactor 12' and communicates with this through a short vertical duct 15- Two pipes 16,17 lead to the reactor 12 respectively for introducing hot water at 50-70°C and milk of lime coming out from a suitable distributor. As it will be better clarified later on, the introduction into the reactor 12' of hot water and milk of lime is made in order to adjust the pH of substances to be treated, and with this aim, inside this reactor 12' a pH pr is provided (not shown in the drawing) - The exit of the reactor 12' is connected to a continuous press 19, the exit of which for the watery fraction # communica t es with the station 3 for separating the fats, and particularly with an accumulation chamber 20, it which communicates the inlet pipe of a pump 21 feeding a sp ll-way settler 22- This is provided with an exchanger 23 for circulating water at 60-80°C and has three distinct exits 23,25,26 respectively for fats, refluent water and calcium sulfate. The operating of the plant according to the invention is the following: the substances to be treated, which are mainly formed by strippines of flesh (shreds of flesh) , that is those filamentous excrescence which are present inside hides to be tanned, as well as those skin coats excessing the desired thickness, are introduced in the mincer 4 which minces them with the aim of increasing the contact surface with the reac n s of the subsequent phases. While the minced product comes out from the mincer 4 it is fed to Mohno pump 7 together with a solution at 20% of sodium metabisulfite, which reacts on the residues adhering to the shreds of flesh; in particular the sulfur present as sulfide is brought to higher valence. It is possible to treat- the product with sodium metabisulfite before or during the mincing. The so treated substance is transferred to the accumulation tank 10 where sodium metabisulfite carries out a slowing action on the oxidative process or putrefaction of the substance which must undergo the subsequent treatments- From the accumulation tank 10 the substance is transferred into the reactor 12, where it is mixed wrth concentrate sulfuric acid at 96-99S& which is at the same time introduced into the reactor with the aim of break up the proteic membranes keeping the fatty bodies. Because of the previuos change caused by sodium metabisul ite on the sulfur, present as sul ide, to take it to higher valence, in this phase there is not emission of sulfuric acid, and however all the fumes emitted in the reactor 12 are sucked up through the duct 14. In particular from this reaction SO2 is emitted which is sucked up and sent to a spray tower (not shown on the drawings) where sulfur dioxide is adsorbed by a dilute solution of caustic soda- When the caustic soda has completely been neutralised by SO,, the so exausted solution is advantageously used to prepare the solution of sodium metabisulfite to be sent to distributor 8- The shred of flesh treated in such a way is then transferred into the reactor 12' in which it occurs its mixing with milk of lime and water at 50-70° C, with the aim of having the whole pH at a value of 5-6 and fluidifying the possible fats having high melting point. This treatment in the ractor 12' has also the function of preventing any possible sulfuring action by the sulfuric acid used in the previuos treatment within the reactor 12. The product co ing out from the reactor 12' , having semifluid consistence, is submitted to mechanical expression in the continuous press 19, which separates a solid fraction - 8 - formed by a proteic compound having a content of humidity of 60-40% which forms the treated product, and by a liquid fraction which is transferred to the spill-way settler 22. Here it is heated by the water circulating in the heater 23 and separated in a mainly lipidic by-product, refluent water and calcium sulfate. The lipidic by-product, which is formed by fat for 80%, and by water for the remaining 20% I can be submitted to the action of a clarifying centrifuge for the complete separation of the two compounds. Alternatively this separation could also occur in a separating centrifuge preceded by a heater. The following example, referring to a pilot plant having a throughput of 1 ton/h (about 1 mσ/h) will better clarify the invention. *. 1 ton/h of shreds of flesh coming out from a fleshing knife machine of the tanning industry has been introduced in the mincer 4, and once minced, has been added with 2 Kg/h of sodium metabisulfite in solution at 20% in the Mohno pump 7, and from this transferred into the accumulation tank 10, where has been let to mature for about two hours. Then it has been transferred into the screw reactor 12, in which also 0,06 ton/h of sulfuric acid has been introduced- After a mixing for about 150 s, the product has beeen - o transferred i .to the reactor 12' , into which 0,02 ton/h of milk of lime and 300 1/h of dilution water have been introduced at the temperature of 55 °C- The product treated in such a way, coming out from the ractor 12' , has been transferred to the continuous press 19, from which abo 0,4 ton/h of shreds of flesh have been obtained and a watery fraction which has been sent to the spill-way settler 22- Here 0,1 ton/h of fats, 1 ton/h of refluent water and 0,03 ton/h of calcium sulfate have been obtained. The water had a C0.D- of 4.000-6.000 mg/1 of 0 2 due, on one hand to inorganic compounds (sulfur in several oxidation states), and on the other end to organic materials (partially destroyed proteins). T' water treated at pH 6 with . iron polysulfate and subsequently lime up to pH 7-8 has been shown purified of the most inorganic pollutants. The waste water had a C0.D. of about 2-000-2.500 and was fit to a subsequent biologic treatment . It has been recognised that the treatment of the refluent water with iron polysolfate can be replaced with a treatment of air oxidation in presence of a catalyst; this treatment has been proved effective but more slow. From what above said it clearly results that the process according to the invention is more advantageous with respect to the traditional process since: - the proteic by-product obtained is substantially without soluble salt content ; - also the refluent water is substantially without salt content ; - there is no risk of air pollution from SOn; - the consumption of reactants is appreciably limited; - the plant is of easy and economic construction as well as of economic maintenance and running which can be carried out also by not-skilled workers. It is fit to intermittent, feeding and therefore it can advantegeously be used in the tanning industry.

Claims: C L A I S 1 - A process for recovering proteins and fats from shreds of flesh and the like characterised by: - mincing the product and treating it with alkaline metabisulfite to prevent the putrefaction and to oxidize the possible sulfides, - letting the product to mature in an accumulation tank, - causing the disgregation of the product by mixing with concentrated sulfuric acid, thus obtaining the separation of proteins and fats from water and sucking up the sulfur dioxide in case emitted, - diluting the fluid compound formed by proteins, fats and water with hot water at 50-70°C thus obtaining a further fluidification of fats and at the same time neutralizing the compound with lime, - submitting the neutralized compound to a continuous pressing for separating solid proteins from water and fats, and - separing the fats from water by deσantation. 2- A process as claimed in claim 1 characterised in that the product is treated w ' th sodium metabisulfite. 3. A process as claimed in claim 2 characterised in that with the sulfur dioxide, in case emitted from the reaction of the product to be treated with sulfuric acid, a solution of diluted caustic soda is neutralised and such exhausted solution is used for the preparation of sodium metabisulfite. 4. A process as claimed in claim 2 characterised in that the product is treated with a solution of sodium metabisulfite at 20%. 5. A process as claimed in claim 1 characterised in that a deep mixing of the product , treated with sodium metabisulfite, with sulfuric acid at 96-98% is carried out. 6. A process as claimed in claim 1 characterised in that it is caused the separation of fats from water through deσantation of the watery fraction co ing out from the continuous press in a spill-way settler- 7. A process as claimed in claim 1 characterised in that it is caused the separation of fats- from water through deσantation of the watery fraction co ing out from the continuous press in a centrifugal separator. 8- A plant to implement the process according to one or more of claims 1 to 7 characterised in that it comprises: - an industrial mincer (4) , - a distributor (8) of alkaline metabisulfite, - an accumulation and maturing tank (10) of the product to be treated, already minced and mixed with alkaline metabisulfite. - a reactor (12,12' ) in which it occurs the mixing of the matured substance with concetrate sulfuric acid and subsequently with hot water and milk of lime, - sucking means (14) for fumes in case emitted from the reac ions within the reactor (12,12'), - press means (19) for separating the products coming out from the reactor (12,12') in a mostly proteic fraction and in a fraction comprising water and fats, - separing means (22) for the water from fats and other solid wastes. 9- A plant as claimed in claim 8 characterised in that the. reactor, in which the product co ing out from the accumulation and maturing tank (10) is treated with concentrate sulfuric acid, is of a two-stages kind, the former (12) for mixing the product with sulfuric acid, the latter (12') for mixing the product with lime and hot water. 10. A plant as claimed in claim 9 characterised in that each stage of the reactor (12,12') is formed by a substant: y cylindrical container, having its axis slightly inclined with respect to the horizontal plane and innerly h ousing a paddle wheel screw. 11. A plant as claimed in claim 8 characterised in that the press (19) is of continuous kind- 12. A plant as claimed in claim 8 characterised in that the separator is formed by a spill-way settler (22) 13- A plant as claimed in claim 8 characterised in that the separator is formed by a centrifugal separator. 14- A plant as claimed in claim 12 characterised in that the spill-way settler (22) is provided with a heater (23) in the zone where the separation of fats occurs- 15- A plant as claimed in claim 14 characterised in that the heater (23) is of hot water feeding kind- 16- A plant as claimed in claim 13 characterised in that a heater is provided between the press (19) and the centrifugal separator.

Inventors: PEZZI ALFREDO, PEZZI, ALFREDO
Applicants: CONTE SRL, CONTE S.R.L.
Application year: 1990
Main classification: C11B1
IPC codes: A23J1, C11B1