Abstract: Provided are a method for recovering gold, in which gold is recovered from a solution containing a gold cyano complex using a crosslinked resin containing a vinyl amine unit, by which gold can be efficiently recovered from the solution not only in a case (A) where a concentration of the gold cyano complex in the solution is low but also in a case (B) where another metal is dissolved in the solution; a method for recovering gold, in which the crosslinked resin and the solution are brought into contact with each other to separate the crosslinked resin and the solution from each other, by which gold can be efficiently recovered from the solution not only in the case (A) but also in the case (B); and a gold recovery facility comprising: a container inside which the crosslinked resin is accommodated in a flowable manner; and a device which feeds the solution to the container, by which gold can be efficiently recovered from the solution not only in the case (A) but also in the case (B).

Abstract: Provided is a polymer flocculant which is capable of controlling the structure of a polymer that is a copolymerization product of a monomer (a) having a structure derived from formula (I) in each molecule and a water-soluble unsaturated monomer (b) having a polymerizable unsaturated bond in each molecule, and which has a branched or cross-linking structure, and is excellent in water-solubility and water dispersibility, In formula (I), R1 and R2 are respectively a linear or branched functional group configured of atoms selected from the group consisting of carbon not having a carbon-carbon unsaturated bond, oxygen, nitrogen, and hydrogen; W is a non-metal element of the group 15; X and Y are each a linear or branched functional group configured of atoms selected from the group consisting of carbon, oxygen, nitrogen, and hydrogen, and each have at least one carbon-carbon unsaturated bond, provided that X and Y have different structures; and Z is a chlorine ion, a bromine ion, or an iodine ion.

Abstract: Provided are a method for producing N-(?-alkoxyethyl)formamide, comprising adding an acid catalyst to the mixed liquid within 3 hours from start of mixing after mixing of N-(?-hydroxyethyl)formamide with an alcohol has been started, by which the N-(?-alkoxyethyl)formamide can be produced at a high yield without additional investment in plant and equipment while suppressing an increase in the temperature of the mixed liquid and preventing corrosion of a pipe; and a method for producing N-(?-alkoxyethyl)formamide, comprising degassing carbon dioxide in the reaction of N-(?-hydroxyethyl)formamide with an alcohol, by which the N-(?-alkoxyethyl)formamide having a decreased carbonate concentration can be produced.

Abstract: A method for producing N-vinylformamide through a vapor-phase thermal decomposition reaction using an evaporator (10) for evaporating a raw material, a thermal decomposition reactor (20) for thermally decomposing a raw material gas generated by the evaporator (10) and a condenser (30) for condensing a thermally decomposed gas generated by the thermal decomposition reactor (20), wherein the evaporation of the raw material is started in the evaporator (10) while the temperature of a tube wall of a first connection tube (40) that connects the evaporator (10) to the thermal decomposition reactor (20) satisfies a requirement represented by formula (1): (temperature of tube wall (° C.))?0.37×(pressure of evaporator (mmHg))+205.

Abstract: Provided are a method for recovering gold, in which gold is recovered from a solution containing a gold cyano complex using a crosslinked resin containing a vinyl amine unit, by which gold can be efficiently recovered from the solution not only in a case (A) where a concentration of the gold cyano complex in the solution is low but also in a case (B) where another metal is dissolved in the solution; a method for recovering gold, in which the crosslinked resin and the solution are brought into contact with each other to separate the crosslinked resin and the solution from each other, by which gold can be efficiently recovered from the solution not only in the case (A) but also in the case (B); and a gold recovery facility comprising: a container inside which the crosslinked resin is accommodated in a flowable manner; and a device which feeds the solution to the container, by which gold can be efficiently recovered from the solution not only in the case (A) but also in the case (B).

Abstract: The present invention relates to a method for producing a vinylamine unit-containing polymer, the method comprising: preparing a mixture for polymerization (a) containing N-vinylformamide as a monomer component by using crude N-vinylformamide which contains the N-vinylformamide and formamide and has a content of the formamide of 1 part by mass or more with respect to 100 parts by mass of the N-vinylformamide; obtaining a polymerization product (b) containing an N-vinylformamide unit-containing polymer and formamide by polymerizing the monomer component in the mixture for polymerization (a); and obtaining a hydrolysis product (c) containing a vinylamine unit-containing polymer through a hydrolysis treatment of the polymerization product (b) using an acid or a base.

Abstract: A method for producing N-(?-hydroxyethyl)formamide which comprises reacting formamide with acetaldehyde in a solvent in the presence of a basic catalyst in a reaction vessel, precipitating the obtained N-(?-hydroxyethyl)formamide in the reaction vessel, and collecting the precipitated N-(?-hydroxyethyl)formamide from the reaction vessel. The production of N-(?-hydroxyethyl)formamide is conducted multiple times using the same reaction vessel so that an (n+1)th reaction is conducted in the reaction vessel in which crystals of the N-(?-hydroxyethyl)formamide obtained in the n-th reaction are present (n is a natural number).

Abstract: A method for producing N-vinylformamide through a vapor-phase thermal decomposition reaction using an evaporator (10) for evaporating a raw material, a thermal decomposition reactor (20) for thermally decomposing a raw material gas generated by the evaporator (10) and a condenser (30) for condensing a thermally decomposed gas generated by the thermal decomposition reactor (20), wherein the evaporation of the raw material is started in the evaporator (10) while the temperature of a tube wall of a first connection tube (40) that connects the evaporator (10) to the thermal decomposition reactor (20) satisfies a requirement represented by formula (1): (temperature of tube wall (° C.))?0.37×(pressure of evaporator (mmHg))+205.

Abstract: Provided are a method for producing N-(?-alkoxyethyl)formamide, comprising adding an acid catalyst to the mixed liquid within 3 hours from start of mixing after mixing of N-(?-hydroxyethyl)formamide with an alcohol has been started, by which the N-(?-alkoxyethyl)formamide can be produced at a high yield without additional investment in plant and equipment while suppressing an increase in the temperature of the mixed liquid and preventing corrosion of a pipe; and a method for producing N-(?-alkoxyethyl)formamide, comprising degassing carbon dioxide in the reaction of N-(?-hydroxyethyl)formamide with an alcohol, by which the N-(?-alkoxyethyl)formamide having a decreased carbonate concentration can be produced.

Abstract: Provided is a polymer flocculant which is capable of controlling the structure of a polymer that is a copolymerization product of a monomer (a) having a structure derived from formula (I) in each molecule and a water-soluble unsaturated monomer (b) having a polymerizable unsaturated bond in each molecule, and which has a branched or cross-linking structure, and is excellent in water-solubility and water dispersibility, In formula (I), R1 and R2 are respectively a linear or branched functional group configured of atoms selected from the group consisting of carbon not having a carbon-carbon unsaturated bond, oxygen, nitrogen, and hydrogen; W is a non-metal element of the group 15; X and Y are each a linear or branched functional group configured of atoms selected from the group consisting of carbon, oxygen, nitrogen, and hydrogen, and each have at least one carbon-carbon unsaturated bond, provided that X and Y have different structures; and Z is a chlorine ion, a bromine ion, or an iodine ion.

Abstract: A method comprising producing N-vinylformamide, polymerizing a monomer ingredient comprising the N-vinylformamide to produce a polymer comprising N-vinylformamide units, hydrolyzing the polymer using an acid or a base to produce an aqueous solution of a polymer comprising vinylamine units, and using the aqueous solution, wherein the storage period (2) from immediately after the production of the polymer to just before initiation of the production of the aqueous solution of a polymer comprising vinylamine units is made longer than the storage period (3) from immediately after the production of the aqueous solution to just before the use.

Abstract: Provided is a method for efficiently producing on an industrial scale a high-performance polyvinylamine solution having good handling properties. After producing a polymer containing N-vinylcarboxamide monomer units having a value of the weight average molecular weight (Mw)/number average molecular weight (Mn) of 5 or higher by aqueous solution standing adiabatic polymerization, the polymer is hydrolyzed in an aqueous solvent in the presence of an alkali and an antigelling agent. In a preferred embodiment of the present invention, a polymer powder having a volatile content of 0.1-12% by mass is obtained by drying and pulverizing after producing a (co)polymer, and the powder obtained is stored or transported to the site of use of the polymer solution and hydrolyzed in an aqueous solvent in the presence of an alkali and an antigelling agent when the polymer solution is needed or at the site of use of the polymer solution.

Abstract: The present invention relates to a method for producing a vinylamine unit-containing polymer, the method comprising: preparing a mixture for polymerization (a) containing N-vinylformamide as a monomer component by using crude N-vinylformamide which contains the N-vinylformamide and formamide and has a content of the formamide of 1 part by mass or more with respect to 100 parts by mass of the N-vinylformamide; obtaining a polymerization product (b) containing an N-vinylformamide unit-containing polymer and formamide by polymerizing the monomer component in the mixture for polymerization (a); and obtaining a hydrolysis product (c) containing a vinylamine unit-containing polymer through a hydrolysis treatment of the polymerization product (b) using an acid or a base.

Abstract: Provided is a precursor for producing polyvinylamine aqueous solution having high storage stability without any decrease in the viscosity of the precursor aqueous solution even with long-term storage when producing polyvinylamine aqueous solution. A powdered N-vinylcarboxamide polymer composition containing N-vinylcarboxamide polymer, the viscosity of an aqueous solution of polyvinylamine obtained by hydrolyzing the polymer being 1.0×106 mPa·s (25° C.) or lower and the content of azo initiator in the aqueous solution being from more than 0 parts by mass to 0.05 parts by mass per 100 parts by mass of polyvinylamine.

Abstract: Provided is a method for efficiently producing on an industrial scale a high-performance polyvinylamine solution having good handling properties. After producing a polymer containing N-vinylcarboxamide monomer units having a value of the weight average molecular weight (Mw)/number average molecular weight (Mn) of 5 or higher by aqueous solution standing adiabatic polymerization, the polymer is hydrolyzed in an aqueous solvent in the presence of an alkali and an antigelling agent. In a preferred embodiment of the present invention, a polymer powder having a volatile content of 0.1-12% by mass is obtained by drying and pulverizing after producing a (co)polymer, and the powder obtained is stored or transported to the site of use of the polymer solution and hydrolyzed in an aqueous solvent in the presence of an alkali and an antigelling agent when the polymer solution is needed or at the site of use of the polymer solution.

Abstract: A process for the preparation of an aqueous solution or dispersion containing a cationic polymer, which comprises the steps of: polymerizing a monomer including an N-vinyl-carboxylic acid amide represented by the general formula CH2═CHNHCOR, wherein R represents a hydrogen atom or methyl group, in an aqueous medium in the presence of either or both of a polyethylene glycol and polypropylene glycol; and then modifying the resulting polymer with an acid or base. Furthermore, an aqueous composition containing a cationic polymer, which comprises (A) a modified N-vinylcarboxylic acid amide polymer, (B) either or both of a polyethylene glycol and polypropylene glycol, and (C) water is disclosed.

Abstract: Disclosed is a process for producing a powdered water-soluble polymer comprising hydrolyzing a copolymer comprising an N-vinylamide unit and a vinyl acetate unit while dispersed in water under a basic condition and then washing the resulting powdered water-soluble polymer with at least one washing liquid selected from an alcohol, water at 20° C. or lower, and salt water.

Abstract: Disclosed is a process for producing a powdered water-soluble polymer comprising hydrolyzing a copolymer comprising an N-vinylamide unit and a vinyl acetate unit while dispersed in water under a basic condition and then washing the resulting powdered water-soluble polymer with at least one washing liquid selected from an alcohol, water at 20° C. or lower, and salt water.

Abstract: A process for the preparation of an aqueous solution or dispersion containing a cationic polymer, which comprises the steps of: polymerizing a monomer including an N-vinylcarboxylic acid amide represented by the general formula CH.sub.2 .dbd.CHNHCOR, wherein R represents a hydrogen atom or methyl group, in an aqueous medium in the presence of either or both of a polyethylene glycol and polypropylene glycol; and then modifying the resulting polymer with an acid or base. Furthermore, an aqueous composition containing a cationic polymer, which comprises (A) a modified N-vinylcarboxylic acid amide polymer, (B) either or both of a polyethylene glycol and polypropylene glycol, and (C) water is disclosed.

Abstract: A database managing system for effecting management in accessing data stored in a database via an index is so configured so as to prevent duplication of index key values and increase of index key values from degrading the access performance and lowering the storage efficiency of the index. Upon receiving, from an application program, a request to add a data record, a database manager adds this data record to a data portion and effects addition and update of an index record in an index portion. An index manager intervenes in this processing and excepts, from the index portion, an index record containing an index key value which has reached an upper limit value of the number of duplications preset in an exception key managing table. At the time of recreation of the index, the index manager refers to access time contained in index records and excepts index records which have not been accessed during an elapse of a fixed period of time.