ENERGY-EFFICIENT SOLVENT-FREE PROCESS FOR THE PRODUCTION OF METAL CHELATES

Description

[0001] The invention relates to the efficient production of amino acid metal chelates and hydroxycarboxylic acid metal chelates, in which, for the production of said chelate complexes, a dry, i.e., solvent-free, mixture of at least one metal compound from the group consisting of metal oxides, metal hydroxides, and metal salts, and at least one solid organic acid comprising at least one chelating acid from the group consisting of alpha- and beta-amino acids and hydroxycarboxylic acids, is subjected to intensive mechanical stress according to claim 1. The invention further relates to the associated metal chelate compositions obtainable by this process, their use, and other compositions containing the process product or the metal chelate compositions according to the invention. State of the art

[0002] Chelates, or synonymously chelate complexes, are coordination compounds in which at least one multidentate ligand, hereinafter also called chelate ligand or "chelator," occupies at least two coordination or binding sites on a central atom. In a chelate complex, one or more chelators can be present per central atom. The central atom is a positively charged metal ion of metals such as zinc (Zn), copper (Cu), manganese (Mn), selenium (Se), iron (Fe), calcium (Ca), magnesium (Mg), nickel (Ni), cobalt (Co), vanadium (V), chromium (Cr), and molybdenum (Mo). In the chelate, some metals occur as cations in only one oxidation state (e.g., Zn 2+< ), while others (e.g., those of Cu, Fe, Ni, Co, V, Cr or Mo) can occur in several oxidation states or as oxocations, for example, molybdenum oxocations in the oxidation states +IV, +V and +VI, and vanadium mostly in the form of vanadyl, VO 2+< .

[0003] It has long been known that trace elements and trace element compounds are present in small quantities ("in traces") in animal, human, or plant organisms and often fulfill vital functions. Their deficiency is evident from the manifestation of deficiency or disease symptoms, general weakness, and / or a reduced reproductive rate. Therefore, it is of great interest to be able to supply these elements in a suitable form.

[0004] It is already known and common practice to use one (or more) organic acid anions containing additional electron donor groups (-NH2, -OH), especially amino acid anions, as chelate complex partners of the respective metal, thus utilizing – in addition to the trace element – ​​the amino acids and / or hydroxycarboxylic acids, which are already frequently administered for supplementation, with their positive physiological effects in the form of a readily bioavailable complex (see, e.g., BKW Ridenour, US5702718 (A) 1997 and the patents cited therein).

[0005] In general, not only natural amino acids, but any organic acids bearing amino and / or hydroxyl groups are suitable for the production of these metal chelates, preferably with these substituents in the alpha or beta position relative to the carboxyl unit. However, the naturally occurring amino acids alanine, arginine (basic), asparagine, aspartic acid (acidic), cysteine, glutamine, glutamic acid (acidic), glycine, histidine (basic), isoleucine, leucine, lysine (basic), methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine are preferably used.

[0006] A suitable method for producing such compounds, which have diverse applications, including as additives in human and animal nutrition, is of significant general interest. Chelation stability should not adversely affect the bioavailability of the amino acid or hydroxycarboxylic acid. Many amino acid chelates even increase the bioavailability of the co-administered central cation compared to a salt or oxide of this cation.

[0007] As scientific studies have now demonstrated, bioresorption from certain chelate compounds is particularly effective in the human and animal organism. Amino acid chelates, in particular, with their moderate degree of chelation via the nitrogen atom, exhibit high bioavailability. As is well documented in the literature and known to experts, significantly higher bioavailability of metals in the form of their chelates has been consistently found than when using corresponding inorganic metal salts.

[0008] According to the current state of the art, the production of suitable amino acid metal chelates as organic trace element compounds is carried out with very low energy efficiency, primarily using wet chemical processes or equally energy-intensive mechanical processes involving grinding media, especially in ball mills. In the latter case, approximately 90% of the energy input is converted into heat (see EP2489670A1). The known wet chemical processes suffer particularly from the unavoidable, energy-inefficient, and consequently costly drying of the material; furthermore, the product is not free of inorganic foreign anions.

[0009] Solvent-free processes are known from the prior art (Rummel, US 2877253 (A) 1959; Ashmead, Pedersen, US 6426424 (B1) 2002; Pedersen, Ashmead, US 6518240 (B1) 2003). While solvent-free processes do not inherently have the aforementioned disadvantage of requiring the removal of large quantities of the solvent, usually water, they do require additional energy when product formation takes place in mechanical mills with grinding media, especially ball mills. The reason for this increased energy consumption is that the grinding media must be set in motion as additional masses, as can be seen, for example, in the process by D. Ramhold, E. Gock, E. Mathies, W. Strauch, EP 2489670 (A1) 2012, in an eccentric vibratory mill (ECM). In the case of using eccentric vibratory mills, the energy required to drive the balancing mass must also be taken into account.Furthermore, in such an inhomogeneously operating vibratory mill system, a comparatively high level of wear is observed on the grinding media themselves due to the high impact stress. This abrasion then undesirably ends up in the product.

[0010] The aforementioned material drying process also becomes relevant in the latter methods, since the reaction water generated during this type of reaction milling must be removed under the influence of heat and / or pressure reduction, requiring additional energy expenditure.

[0011] Another disadvantage of the aforementioned solid-state processes for obtaining metal chelates is the sometimes considerable size and structural heterogeneity of the resulting solid products. For example, the process described in EP 2 489 670 A1 produces needle-shaped metal-amino acid chelate structures with an average particle size of 40 to 60 µm, whereby up to 80% of the particles have a particle size greater than 0 to 100 µm and up to 2% have a particle size greater than 500 µm, i.e., a value ten times higher than the "average size" of 50 µm, thus resulting in considerable granularity.

[0012] WO 2013 / 11 07 89 A1 describes active ingredient / carrier inclusion compositions produced by a mechanochemical activation process using high-energy liquid jet mills.

[0013] Significant structural heterogeneity generally complicates the further processing of the resulting metal-chelate complexes, such as sorting by particle size, precise dosing, and homogeneous mixing with other substances. The drug release kinetics are also adversely affected by particle size heterogeneity. A strongly needle-like morphology impairs the free-flowing and spreading properties of the particulate product. Needle-shaped crystals of the complexes, which are not readily soluble in water and may even be acid-insoluble, could have harmful effects if ingested by humans or animals. Needle-like structures should therefore be avoided.

[0014] The invention is therefore based on the objective of avoiding, as far as possible, the disadvantages of the prior art with regard to the manufacturing process and of providing metal chelates of other morphologies. The aim is to provide an energy-efficient process with good yield and high selectivity. By-products and decomposition products, in particular of the organic-chemical complex ligands, are to be avoided.

[0015] The problem is solved by the method according to claim 1 and the particular process product, namely the produced metal chelate and the metal chelate composition according to claims 7 and 8, the uses according to claim 13 and the compositions according to claim 14. Advantageous embodiments of the invention are specified in the dependent claims.

[0016] The starting materials for the process are in a solid state. Their particle size can correspond to a typical, commercially available fine-grained or fine-crystalline form. Pre-grinding of the starting materials is generally not necessary. The metal oxides used, e.g., zinc oxide and copper oxide, are available with particle sizes between 150 and 300 µm and can be used as such. The solid organic acids are commercially available with particle sizes of approximately 200 to 500 µm and can be used directly as obtained, i.e., in commercially available particle sizes.

[0017] Metal compounds selected from the following groups are used to provide the central atom: metal oxides, metal hydroxides (including mixed oxides and hydroxides), inorganic metal salts, and organic metal salts. Amino acids and / or hydroxycarboxylic acids are used as the chelating ligands, i.e., as chelating organic acids. Other non-bidentate ligands may also be included. The starting materials can be used premixed, or they can be fed individually to the fluidized bed counterjet mill serving as the reactor and mixed in a separate unit or directly in the mill's grinding chamber. Metal oxides, metal carbonates, and metal oxalates are preferred for the metal compound.

[0018] According to the invention, the reactants, i.e., at least the metal compound used and the organic acid, are introduced in particulate form into a fluid jet of a fluidized bed counterjet mill operating without grinding media, as described in claim 1. It is essential that all reactants are fed into a collision zone in the milling chamber, where particle-particle collisions in the milling gas jet, and especially in the center of these jets, provide sufficient excitation of the reactants and the activation energy for the desired complexation reaction. In the use of the fluidized bed counterjet mill according to the invention, this occurs primarily in the same zone where, in conventional use, the "milling" (here, "jet milling") takes place, i.e., the comminution of the solid particles, which may also occur in this case.The grinding chamber encompasses the reaction zone and forms a reaction space for the reactive grinding process. The process can be carried out continuously by continuously feeding the reactants. The fluidized bed jet mills used require significantly less energy not only than mills with grinding media, but also less energy than conventional jet mills, in which the material to be ground is introduced into the grinding chamber by the grinding gas stream, resulting in friction between the material and the mill wall. Furthermore, unlike conventional ball mills and even conventional jet mills, the fluidized bed jet mill operates almost wear-free.

[0019] In summary, within a reaction space formed in a jet region of the fluid jet or several fluid jets, a mechanical activation of at least one of the reactants is effected by particle collision processes, triggering a solid-state reaction to the metal chelate.

[0020] The process is based on accelerating particles using a high-pressure milling gas stream and then colliding these particles, particularly at the focal point of opposing milling gas nozzles. The resulting collisions generate such a high energy input that the respective organic acid and the metal source react to form a chelate.

[0021] The oxygen from the metal component forms pure water, which is carried away with the milling gas stream due to the high air rates of the process. Therefore, no additional energy is required.

[0022] Regarding product formation, it is assumed that particle collisions, particularly in the center of the gas jets, triggered by jet velocities typically ranging from 300 m / s to 1000 m / s, lead to lattice defects resulting from the described point loadings. Even at room temperature and 6 bar overpressure, milling gas velocities of 500 m / s are achieved. These lattice defects are likely primarily present in the high-specific-gravity metal compound used and enable the subsequent reaction to form the amino acid metal chelate. Prior energy-intensive activation, as required in corresponding reaction milling processes in an eccentric vibratory mill (e.g., according to D. Ramhold, E. Gock, E. Mathies, W. Strauch, EP2489670 (A1) 2012), is not necessary, resulting in further energy savings.High values ​​of the specified grinding gas velocities, with a corresponding advantage for the extent of particle-particle collisions in the grinding chamber of the fluidized bed counterjet mill, are achieved particularly when the grinding gas, which is naturally hot in the compressor, is not cooled in an energy-intensive way (as is otherwise usual), but is used directly as hot gas.

[0023] The metal chelate can be a "pure" chelate, made from a metal compound and an amino or hydroxy carboxylic acid, or a mixed product in which metal oxides of different metals and / or several different acids are used in combination.

[0024] The product is separated in a product filter downstream of the fluidized bed counterjet mill.

[0025] The disadvantages of the technically and / or energetically unfavorable processes known from the prior art can thus be avoided. The invention is based on the finding that fluidized bed counter-jet mills, originally designed for fine grinding, enable such a high energy input into the material being ground that, with a suitable selection of the starting materials and operating conditions, a mechanochemical reaction occurs solely through collisions between the materials, without the need for grinding media or other friction surfaces.

[0026] In contrast, in previously reported cases, such a solid-state reaction in ball mills (centrifugal mills, eccentric vibratory mills, see e.g., B.D. Ramhold, E. Gock, E. Mathies, W. Strauch, EP2489670 (A1) 2012) is triggered by collisions with grinding media. The mechanisms of such mechanochemical reactions are generally assumed to involve enormous point loads accompanied by high local temperatures (see e.g., B.V. Boldyrev, K. Meyer, Solid-State Chemistry, VEB Verlag für Grundstoffindustrie, Leipzig, 1973; D. Margetic, V. Strukil, Mechanochemical Organic Synthesis, Elsevier Science Publishing Co., Inc., 2016). The temperature-sensitive organic chemical ligands, namely the amino acids and / or hydroxycarboxylic acids, can be subject to undesirable degradation reactions.

[0027] In the present case according to the invention, however, no grinding media are present. Since no additional masses need to be set in motion, considerable amounts of energy can be saved in this way. Furthermore, the resource-saving process according to the invention in a fluidized bed counterjet mill has the advantage that the end product is free of corresponding metal abrasion due to the described absence of (steel) grinding media. Likewise, the organic ligands are preserved. The tendency for side reactions and degradation reactions within the ligands is drastically reduced, since no heat is introduced into the process, neither for a thermal reaction nor due to strong mechanical activation with material mass.

[0028] Since the process is solvent-free, the associated solvent exposure is eliminated, both during production and in the product itself. The product is not subjected to thermal stress from heat drying. The problematic technical use of salt solutions is also eliminated, as is the disposal of significant quantities of residual salts as byproducts. Due to the synthesis process, the products are preferably free of sulfur and sulfates and generally free of salt anions not required by the process.

[0029] According to the invention, a fluidized bed counterjet mill is used in which particle collisions take place at the center of several mutually directed fluid nozzles. A counterjet arrangement is any arrangement in which the counterjet principle is applied regardless of the specific angle between the fluid nozzles or grinding gas nozzles. The fluid nozzles or grinding gas nozzles can preferably be arranged at angles between 180° and 60° to each other, whereby the jets of the "counterjet nozzles" must intersect to create a collision chamber, which, according to the invention, is used as a reaction chamber.

[0030] InIn a preferred embodiment, a fluidized bed is formed in a fluid flow section at the intersection of the jet directions of at least two fluid nozzles, together with the introduced particulate reactants, which provides the reaction space for chelation. Two to six fluid nozzles operating in counter-jet mode are currently considered preferred, and two to four fluid or milling gas nozzles are even more preferred.

[0031] In In preferred embodiments, the fluidized bed counterjet mill is operated with flow velocities of about 100 to 1000 m / s, preferably 250 to 1000 m / s, more preferably 300 to 1000 m / s, in particular 300 to 700 m / s and a grinding gas pressure of about 5 to 10 bar, preferably about 7 to 8 bar.

[0032] The reactants provided at the mill inlet or for feeding into the mill, i.e., the solid particulate metal hydroxide, metal carbonate, or metal oxalate and the solid amino and / or hydroxycarboxylic acid(s), are fed in as "reaction material" instead of the conventional pure milled material. This is done—generally from one or more storage containers (reservoirs), or alternatively in batches from bags—preferably by means of an independent conveying device, for example, a chute or a feed line with or without additional conveying equipment.

[0033] By using a fluidized bed counterjet mill, the reactant is introduced directly into the grinding chamber; in this way, the gas passed through the nozzles is kept free of particles of the starting material, which could otherwise cause wear and abrasion there, as is the case with conventional jet mills due to the material transport through the nozzles and even more so with classic mills with grinding media (especially ball mills).

[0034] According to a particularly preferred embodiment, the reactants are transported into the grinding chamber by means of a conveying device and reach the reaction space inside the grinding chamber by free fall. The conveying device preferably comprises at least one screw conveyor.

[0035] The particle size of the final product can be adjusted by selecting the operating conditions of the fluidized bed counterjet mill with the classifier wheel, which is usually also fitted as standard for fine grinding, typically to the medium to small single-digit micrometer range (mean diameters, determined in a professional manner, for example by laser diffractometry).

[0036] The process product is compact and fine-grained. The compact structure is virtually free of crystal needles, and there is no significant amount of sprayed particles. More than 80% of the particles have an ellipsoidal or cuboidal structure, with a size ratio of the longest to the shortest particle diameter of less than 4:1. Due to the compact, fine-grained structure, a comparatively large surface area is also achieved, which has a positive effect on the product's flowability, dry miscibility, dispersibility, and dosing accuracy, as well as on the formulation of any products. The process products can thus be incorporated more easily into mixtures and pellets and are distributed more uniformly within them.

[0037] The product is exceptionally fine-grained with a narrow particle size distribution. This is evident, for example, in the ratio of the D-values: D99, D90, D50, (D10). The D-value indicates the percentage of particles smaller than the diameter value specified for that particular D-value. The percentage is expressed as a subscript, i.e., D90 = ... means "90% of the particles have a (volumetrically determined) diameter smaller than...". The corresponding data are obtained using laser diffractometry.

[0038] Compared to known energy-intensive solid-state processes using grinding media, a particularly compact and homogeneous particle size is achieved. For example, the needle-shaped chelate particles described in patent application EP 2389670 A1 and shown in an electron micrograph have a mean particle size of 40–60 µm, with up to 80% of the particles in the 0–100 µm range, corresponding to a D80 value of 100 µm. In contrast, the invention achieves a very steep, far more homogeneous and defined particle size distribution, and the particles are, with a mean particle diameter of typically 1.5 to 3.5 µm (instead of 40 to 60 µm in the ESM process, see above), more than an order of magnitude smaller overall.This is advantageous for subsequent process steps, particularly the mixing of defined amounts of chelate with defined amounts of other substances, because a homogeneous particle size distribution significantly facilitates automated processing. The risk of clumping is reduced, and the mechanical components of sorting, measuring, dosing, and filling systems can be better adjusted to a specific chelate crystal size. Certain post-processing steps, such as grinding the generated chelate crystals to achieve a homogeneous, sufficiently small particle size, can be eliminated.

[0039] Often, minute quantities of metal acid chelates are mixed with, for example, 1000 times the amount of other substances, e.g., in animal feed or when used as catalysts. To be able to add a defined amount of chelates and mix them homogeneously with other substances, a homogeneous, clearly defined particle size of the chelates is very advantageous.

[0040] The process product according to the invention forms compact crystals, i.e., practically needle-free and without a significant proportion of granules. When administered to humans or animals, the adverse health effects associated with the needle-shaped chelate crystals found in the prior art no longer occur.

[0041] It must be emphasized that the reaction milling process according to the invention in a fluidized bed counterjet mill is entirely autogenous, in that all the energy for product formation, including the necessary activation energy, is provided exclusively by the gas jet. Neither an external temperature increase is required, nor does an uncontrolled (potentially product-damaging) temperature increase of the materials used occur, as is the case with conventional reaction milling processes during the course of the process, primarily due to impact and friction of the milling media themselves. Furthermore, the process according to the invention has the advantage that, unlike reaction milling in a conventional ball mill, usually an eccentric vibratory mill, a fluidized bed counterjet mill allows for continuous process operation and thus a higher throughput with lower specific energy consumption.

[0042] A comparative calculation of the respective specific energy consumption in an eccentric vibratory mill (single-module, ESM 504, Siebtechnik GmbH, Mülheim an der Ruhr) and in a fluidized bed counterjet mill (CGS 71, Erich NETZSCH GmbH & Co. Holding KG, Selb) is given in the following section: Eccentric vibratory mill ESM 504: Power (drive + mixer): 27.5 kW Throughput: 40 kg / h Grinding media: Cylpeps 32 mm x 32 mm (steel) Specific energy consumption [kWh per ton]: 27.5 kW / 40 kg / h x 1000 kg = 688 kWh / t Fluidized bed counterjet mill CGS 71: Airflow: 1920 m³ / h (8 bar, 20°C; ISO 1217) Classifier wheel power: 15 kW Compressor power (1956 m³ / h, main drive + separate fan): 206 kW Throughput: 500 kg / h Specific energy consumption [kWh per ton]: 221 kW / 500 kg / h x 1000 kg = 442 kWh / t

[0043] Unlike a fluidized bed counterjet mill, an eccentric vibrating mill can only operate in batches.

[0044] The specific energy consumption per ton of product in the case of the use of a fluidized bed counterjet mill according to the invention is therefore more than one-third lower than the consumption of a conventional production plant for amino acid metal chelates based on an eccentric vibratory mill. Furthermore, the present process is characterized by the fact that it does not require catalytically active reagents (such as iron ions) and avoids energy-intensive upstream or downstream process steps (such as spray drying).

[0045] According to the invention, an efficient, solvent-free process for the production of complex compounds from chelating metals as described in claim 1, preferably zinc, copper, manganese, selenium, iron, calcium, magnesium, nickel, cobalt, vanadium, chromium, or molybdenum, preferably zinc, copper, and selenium, and solid organic acids, preferably naturally occurring amino acids, preferably glycine, methionine, lysine, and / or cysteine, but also alanine, arginine, asparagine, aspartic acid, glutamine, glutamic acid, histidine, isoleucine, leucine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine, is now available. In general, all chelating amino and / or hydroxycarboxylic acids are suitable, both of synthetic and natural origin.

[0046] The conversion is achieved solely by subjecting a mixture of the respective metal compound, preferably in the form of oxides, in particular ZnO, CuO, Fe 2 O 3 , Mn 2 O 3 or corresponding oxides of other metals desired for the products to be produced, or in the form of oxalates or carbonates of the selected metals for the compounds to be produced, in a mixture with the solid organic acid (preferably with the participation of at least one amino acid), as described above, to mechanical stress in a fluidized bed counterjet mill.

[0047] The reaction rate during the mechanochemical solid-state reaction depends on the operating conditions of the fluidized bed counterjet mill that are essential to the invention (including the milling gas flow and pressure, the type and temperature of the milling gas or fluid, preferably air, optionally also nitrogen, argon, carbon dioxide or steam, and the classifier rotation speed as well as the feed rates of the starting materials). Crucial for the onset of the solid-state reaction are also the entry velocity of the supplied gas, and thus in particular the geometry, dimensions and arrangement of the jet nozzles, as well as the degree of enrichment of the reaction material in the reaction chamber.

[0048] Suitable fluidized bed counterjet mills are an industrial standard, particularly for applications requiring contamination-free comminution, and have been known for a long time (see e.g. BPM Rockwell, AJ Gitter, Am. Ceram. Soc. Bull. 1965, 44, 497-499). For about 20 years, the development and optimization of such fluidized bed counterjet mills have been the subject of renewed intensive research (see, e.g., BPB Rajendran Nair, SS Narayanan, From World Congress on Particle Technology 3, Brighton, UK, July 6-9, 1998 (1998), 2583-2595; M. Benz, H. Herold, B. Ulfik, Int. J. Min. Proc. 1996, 44-45, 507-519; Z. Korzen, R. Rink, A. Konieczny, Zeszyty Naukowe - Politechnika Lodzka, Inzynieria Chemiczna i Procesowa 1997, 22, 141-150; H. Berthiaux, J. Dodds, Powder Technol. 1999, 106, 78-87; H. Berthiaux, C. Chiron, J. Dodds, Powder Technol. 1999, 106, 88-97). The fine or... is frequently the goal.Fine grinding down to the single-digit micrometer range, with parameter optimizations often focusing on application to pharmaceutical products (see e.g. BPWS Heng, LW Chan, CC Lee, STP Pharma Sciences 2000, 10, 445-451 or LW Chan, CC Lee, PWS Heng, Drug Development Ind. Pharm. 2002, 28, 939-947).

[0049] The considerable potential energy input manifests itself, for example, in the possible comminution of even very hard materials, including silicon carbide or aluminum oxide (Y. Wang, F. Peng, Part. Sci. Technol. 2010, 28, 566-580; Y. Wang, F. Peng, Powder Technology 2011, 214, 269-277; MX Zhang, HY Chen, CP Yan, LY Lin, Rev. Adv. Mat. Sci. 2013, 33, 77-84).

[0050] The actual process of a chemical reaction, characterized by the breaking and subsequent reformation of chemical bonds, thus reaction milling under the operating conditions of fluidized bed jet mills, has never before been utilized in a manner according to the invention. An example of surface modification of ZnO nanoparticles can be found in: X. Su, Z. Cao, Q. Li, Z. Zhang, J. Adv. Microscopy Res. 2014, 9, 54-57 and in: X. Su, S. Xu, T. Cai, Guangzhou Huagong 2012, 40, 101-102, both on the topic of "jet grinding / jet milling" and surface modification.

[0051] The invention leads to process products with novel, previously unattainable product properties and comprises a structurally homogeneous product, novel in this form, with a very narrow particle size distribution. The fine grain size of the product is also particularly noteworthy.

[0052] The object of the invention is therefore further solved by a metal chelate composition according to claim 8, comprising at least one metal chelate compound with a multivalent metal cation and at least one chelate ligand comprising at least one chelating acid from the group of alpha and beta amino acids and hydroxycarboxylic acids, wherein the compound is in the form of particles with a particle size in the single-digit micrometer range - i.e., a mean particle diameter of ≤ 5 µm (D 50 = 1 to 5 µm) - as already described above in connection with the process.

[0053] The metal chelate composition contains or consists of at least one metal chelate compound.

[0054] The invention comprises metal chelate compounds that are directly obtained as process products of the process according to the invention, i.e., the pure metal chelate compounds formed due to the stoichiometric composition of the starting materials, and also comprises compositions that contain these metal chelate compounds alongside other substances, which may primarily be residues of the starting materials or additives or further substances that complement the composition and were added to the mill during the process.

[0055] The metal-chelate compound is a coordination compound (also called a complex compound, complex), as already described, with at least one central atom consisting of a polyvalent, i.e., at least divalent, metal cation and at least one chelating ligand comprising at least one organic, chelating, i.e., at least bidentate with respect to complexation, organic acid selected from the group of alpha- and beta-amino acids and hydroxycarboxylic acids. The amino acids can be natural amino acids, especially essential amino acids, but also bidentate synthetic amino acids.

[0056] Within the scope of the invention, it is not excluded that, in addition to the specifically mentioned and claimed ligands, other ligands, namely other bidentate or simply coordinating ligands and / or monovalent or polyvalent anions, are present in the metal chelate compound. This may be desirable, for example, to expand the range of applications of the metal chelate compositions according to the invention.

[0057] A preferred complexing acid that can be incorporated into the chelate complex as a ligand alongside at least one amino acid or hydroxycarboxylic acid is nicotinic acid. The corresponding products are amino acid-nicotinic acid metal chelates, such as copper nicotinate glycinate or selenium nicotinate methionate.

[0058] The metal chelate compounds and metal chelate compositions according to the invention are dry, solid, particulate substances or products with a characteristic structure and size distribution.

[0059] According to the invention (see also claims 1 and 8), the metal chelate compound is in the form of particles, 90% of which have a mean particle diameter (individual particle diameter) of a maximum of 15 µm and 50% of which have a mean particle diameter (individual particle diameter) of a maximum of 5 µm (D 90 ≤ 15 µm; D 50 ≤ 5 µm). The average particle diameter (average over all particles of a sample) for these embodiments is between 1 µm and 5 µm.

[0060] Typical D50 values ​​for individual samples range between 1.5 and 4.5 µm.

[0061] Typical D90 values ​​for individual samples range between 4 and 6 µm. D90 is preferably less than or equal to 15 µm and further preferably D90 ≤ 7 µm.

[0062] Typical D99 values ​​for individual samples range between 8 and 15 µm. D99 is preferably less than or equal to 20 µm, and more preferably D99 ≤ 15 µm.

[0063] No splashing occurs with respect to these values, because the largest particles according to the invention have sizes below 25 µm (D 99.9 ≤ 25 µm, at the same time sieve exclusion limit < 25 µm).

[0064] Furthermore, the particle size distribution of the process products according to the invention is significantly narrower than previously available, as shown from Fig. 2c This is evident. This significantly distinguishes the product according to the invention from known products obtained by wet or dry chemical processes.

[0065] Due to its fine particle size and relatively uniform particle dimensions, the metal chelate or metal chelate composition obtained by the process according to the invention is easy to dose, free-flowing, and readily miscible and dispersible when dry. The fine microstructure can also have a positive effect on the absorbability of the products.

[0066] The metal chelate compound according to the invention is free of mill and grinding media abrasion.

[0067] Preferably, the metal chelate compound is completely free of chloride and / or sulfate ions as ligands.

[0068] The metal chelate composition is further preferably characterized in that the stoichiometric ratio (mol ratio) of chelating acid to metal compound - in the case of a chelate mixture, based on each individual chelate compound - is from 0.5 to 1 to 4 to 1. In In particular embodiments, the metal chelate compound or at least one metal chelate compound contained in the metal chelate composition according to the invention is a 2:1 amino acid metal chelate compound, preferably of zinc or copper, or a 3:1 amino acid metal chelate compound, preferably of iron or manganese.

[0069] As the analysis described below clearly shows, the process according to the invention makes it possible to obtain highly defined, chemically pure chelates, as demonstrated by the IR spectra of selected metal-amino acid 1:2 chelates. Since amino acid chelates are considered to be particularly well absorbed, or their components possess a particularly high bioavailability, the high degree of conversion and the chemical purity of this product represent a significant quality advantage of the products according to the invention. The quality is further enhanced by the absence of metal abrasion, especially since no grinding media are used, and by the product's unique morphology.

[0070] In general, a wide variety of central atoms can be selected. In preferred embodiments, the metal of one or at least one of the metal chelate compounds is selected from the group consisting of zinc (Zn), copper (Cu), manganese (Mn), selenium (Se), iron (Fe), calcium (Ca), magnesium (Mg), nickel (Ni), cobalt (Co), vanadium (V), chromium (Cr), and molybdenum (Mo).

[0071] In preferred embodiments, the chelating organic acid of the metal-chelate composition according to the invention is selected from the group consisting of alpha-hydroxy carboxylic acids, beta-hydroxy carboxylic acids, natural amino acids, essential amino acids or synthetic amino acids.

[0072] The metal chelates according to the invention particularly comprise the following types of substances and substances: zinc bisglycinate, zinc bislysinate, zinc bismethionate, copper bisglycinate, copper bislysinate, copper bismethionate, (selenium methionate, selenium encysteinate), iron bisglycinate, iron trisglycinate, iron bislysinate, iron trislysinate, iron bismethionate, iron trismethionate, manganese bisglycinate, manganese trisglycinate, manganese bislysinate, manganese trislysinate, manganese bismethionate, manganese trismethionate.

[0073] The metal chelates according to the invention can be used in the usual manner. In particular, the following uses should be mentioned: in a feed additive, in a foodstuff, as a food supplement, as a pharmaceutical, as an antiseptic, in a pharmaceutical composition, as a cooking additive, as a fertilizer additive, in a seed treatment agent, in a plant protection product, as a catalyst for chemical reactions, or in an electroplating additive. The invention therefore also includes compositions for the aforementioned uses, which are prepared or manufactured for these uses and contain the process product of the process according to the invention, i.e., the metal chelate composition, as described in more detail above. EXAMPLES OF EXECUTION

[0074] The essential effect of the mechanochemical treatment of metal oxides, metal carbonates, or metal oxalates with an organic acid, preferably an amino acid, in a fluidized bed jet mill is explained below using several examples. The reaction milling processes of the inventive method are carried out on a scale of 2 to 22 kilograms by way of example. This does not represent a limitation. In principle, considerably larger fluidized bed jet mills can also be realized as reactors for chelate production by adjusting the dimensions, both with larger individual feed quantities and for continuous operation. Larger fluidized bed jet mills for jet milling are already industrially available. The exemplary embodiments given refer to a fluidized bed opposed jet mill from the manufacturer Hosokawa Alpine, Augsburg, designated AFG 100 and AFG 400, respectively.from the manufacturer Netzsch, Hanau, with the designation CGS 10. Example 1:

[0075] In a fluidized bed counterjet mill, 1.501 kg of glycine (20.0 mol) and 0.814 kg of zinc oxide (10.0 mol) are milled together for 45 minutes at an airflow of 50–80 m³ / h, a milling gas pressure of 7.0 bar, and a classifier rotation speed of 18,000 s⁻¹. An IR spectroscopic analysis of the final product ( Figure 4 The IR spectrum shows the almost complete conversion (> 95%) of the aforementioned amino acid to the corresponding zinc glycinate (synonyms according to Chemical Abstracts Service CAS: a) bis(Glycinato-N,O)zinc, b) Bis(glycinato)zinc, c) Glycine zinc salt, d) Glycine, zinc complex, e) Zinc bisglycinate, f) Zinc glycinate, g) Zinc(II) glycinate, h) Zinc, bis(glycinato)-). This IR spectrum corresponds to that of a commercially available reference, CAS: 14281-83-5). Example 2:

[0076] In a fluidized bed counterjet mill, 1,940 kg of methionine (13.0 mol) and 0.529 kg of zinc oxide (6.5 mol) are milled together for 45 minutes at an airflow of 50–80 m³ / h, a milling gas pressure of 7.0 bar, and a classifier rotation speed of 18,000 s⁻¹. An IR spectroscopic analysis of the final product ( Figure 5 ) shows the almost complete conversion of the mentioned amino acid (> 95 %) to the corresponding zinc methionate (Chemical Abstracts Number, CAS: 40816-51-1). Example 3:

[0077] In In a fluidized bed counterjet mill, 1,900 kg of lysine (13.0 mol) and 0.529 kg of zinc oxide (6.5 mol) are milled together for 45 minutes at an airflow of 50–80 m³ / h, a milling gas pressure of 7.0 bar, and a classifier rotation speed of 18,000 s⁻¹. The end product, zinc lysinate, is also obtained with a purity > 95%. Example 4:

[0078] InIn a fluidized bed counterjet mill, 1.576 kg of glycine (21.0 mol) and 0.835 kg of copper oxide (10.5 mol) are milled together for 50 minutes at an airflow of 50–80 m³ / h, a milling gas pressure of 7.0 bar, and a classifier rotation speed of 18,000 s⁻¹. The end product, copper glycinate, is also obtained with a purity > 95%. Example 5:

[0079] In In a fluidized bed counterjet mill, 1.791 kg of methionine (12.0 mol) and 0.477 kg of copper oxide (6.0 mol) are milled together for 55 minutes at an airflow of 50–80 m³ / h, a milling gas pressure of 7.0 bar, and a classifier rotation speed of 18,000 s⁻¹. The final product, copper methionate, is also obtained with a purity >95%. Example 6:

[0080] InIn a fluidized bed counterjet mill, 1,900 kg of lysine (13.0 mol) and 0.517 kg of copper oxide (6.5 mol) are milled together for 50 minutes at an airflow of 50–80 m³ / h, a milling gas pressure of 7.0 bar, and a classifier rotation speed of 18,000 s⁻¹. The final product, copper lysinate, is also obtained with a purity of > 95%. Example 7:

[0081] In a fluidized bed counterjet mill, 13.51 kg of glycine (180 mol) and 7.33 kg of zinc oxide (90 mol) are milled together for 4.5 minutes at an airflow of 800–1200 m³ / h, a milling gas pressure of 7.0 bar (80 °C, uncooled compressor air), and a classifier rotation speed of 4,650 s⁻¹. The corresponding zinc glycinate is characterized by IR spectroscopy. The yield corresponds to a throughput of 280 kg / h.

[0082] For a better illustration of the invention, reference is made to the attached figures. These show: Fig. 1: Schematic diagram of a device for reaction milling in a fluidized bed jet mill; Fig. 1a: Side view; Fig. 1b: Top view; Fig. 2a: SEM image of zinc glycine chelate (left); Fig. 2b: SEM image of zinc oxide (right); Fig. 2c: Particle size distribution measured on zinc bisglycinate; Fig. 2d: SEM image of copper glycinate; Fig. 3: ATR-IR spectrum of glycine; Fig. 4: ATR-IR spectrum of methionine; Fig. 5: ATR-IR spectrum of zinc glycine chelate; Fig. 6: ATR-IR spectrum of zinc methionine chelate; Fig. 7: ATR-IR spectrum of copper glycine chelate.

[0083] Figure 1 shows a schematic representation of reaction milling in a fluidized bed counter-jet mill 10,The sketch is limited to the essential elements of the device. Additional device elements, not shown here, include those for feedstock supply and delivery, product discharge, control and regulation, and the like.

[0084] The fluidized bed counterjet mill shown is a commercially available model used, for example, for the fine grinding of solids (milling, "jet milling"). The example shown here is a fluidized bed counterjet mill with a three-nozzle system.

[0085] Figure 1a The device shown is the fluidized bed counterjet mill. 10, schematically in a sectional view from the side, Figure 1b Figure 10 shows the same fluidized bed counterjet mill in a sectional view from above, showing the nozzle arrangement. Identical parts are marked with the same reference numerals.

[0086] As in Figure 1aAs can be seen, a grinding chamber 1 is connected via a feed line 2 to a grinding material reservoir 3, from which the grinding material is fed into the grinding chamber 1. In this embodiment, the solid, premixed reaction grinding material is introduced from the reservoir 3 into the grinding chamber 1 by free fall and thus without additional energy expenditure through the feed line 2. The grinding chamber 1 provides or comprises a reaction space 1 for the reaction grinding according to the invention.

[0087] Alternatively, it would also be possible to provide internal components, such as distributing components, in the supply line 2, as well as additional conveying means, particularly if the feed is not from above but, for example, from the side. Furthermore, in alternative embodiments not shown here, it is possible to hold the reactants in several separate reservoirs and either mix them directly in front of the grinding chamber 1, which can take place in one of the supply lines 2 or in a separate mixing chamber, or to feed the reactants separately and in metered amounts from the respective reservoirs into the grinding chamber 1, where mixing can take place within the grinding chamber itself.

[0088] The fluidized bed counterjet mill 10 has at least two fluid nozzles. 4, which must be aligned against each other or arranged at an angle to each other in order to create a collision zone in the center of the nozzle arrangement.

[0089] As from Figure 1b As can be seen in the example shown, three fluid nozzles 4 are depicted for the grinding gas supply, whereby the nozzles or jet direction vectors intersect in a narrowly defined zone where the particles collide and subsequently react with each other. The fluid nozzles 4 are in a plane perpendicular to the plane of the drawing. Figure 1a The nozzles are arranged and lie in the plane of Figure 1b, each oriented at an angle of 120° to the others. A fluidized bed 5 of ground material and gas is formed in the center of the nozzle arrangement, i.e., in a collision zone created by the gas jets exiting the fluid nozzles 4.

[0090] The milled material particles located in the center of the mutually directed fluid nozzles 4 within the fluidized bed and the actual reaction space 5 formed thereby - here the reaction partners for the chelate formation reaction according to the invention - are accelerated by the gas flow in such a way that after the particle collisions the chemical reaction and the associated product formation is triggered.

[0091] The actual reaction chamber 5, The area in which the solid-state reaction takes place is located in the fluidized bed within the collision zone described above.

[0092] Figure 2a shows a SEM image of a sample of a zinc glycinate (zinc bisglycinate) produced according to the invention in comparison to the zinc oxide (ZnO) used as a starting material for the metal compound in Figure 2b .

[0093] It is clearly evident that the inventive method forms compact particles without a significant proportion of shot grain, i.e., no needles, as shown on the right in Figure 2b The zinc oxide starting material is recognizable. This results in improved processability and flowability of the product. The particle sizes are in the small single-digit micrometer range with a relatively narrow particle size distribution. The product is therefore very homogeneous and has a comparatively large surface area. This makes the product particularly easy to disperse, for example, in more complex compositions, and to dose, as well as to compact. Since no unwanted foreign salts or byproducts are present, the amino acid and metal density in the product is high.

[0094] The grain size distribution of the in Figure 2aThe zinc bisglycinate shown, produced according to embodiment 1, was investigated in more detail using laser diffractometry. The results are presented in Figure 2c graphically represented.

[0095] The vast majority of particles have a diameter between approximately 1 and 4 µm. The narrow particle size distribution evident from the single-diameter curve shows typical ratios for the (volumetric) D10, D50, and D90 values. 99% of the particles have a diameter of less than 10.00 µm (D 99 ), 90% of the particles have a diameter of less than 6.82 µm (D 90 ), 50% of the particles have a diameter of less than 3.41 µm (D 50 ) and 10% of the particles have a diameter of less than 0.86 µm (D 410 ).

[0096] Further tests on other amino acid chelates according to the invention yielded D50 values ​​between 1 and 5 µm. Preferably, D50 is therefore between 1 and 5 µm, and more preferably between 1.5 and 3.5 µm.

[0097] The D90 values ​​are preferably between 4 and 7 µm, the D99 values ​​were less than 15 µm in each of the cases examined.

[0098] Figure 2d shows a SEM image for another product according to the invention, namely a copper bisglycinate produced according to embodiment 4.

[0099] The images of the different amino acid chelates (for ZnGly 2 and CuGly 2) clearly demonstrate that the process yields uniformly homogeneous and fine-grained amino acid chelates regardless of the starting compound.

[0100] Figures 3 to 7 show infrared spectra, which will be discussed in more detail below. Analytics

[0101] In the case of the production of amino acid metal chelates according to the invention, the analysis of such compounds, and thus the proof of the occurrence of a (mechano)chemical reaction, is carried out on the basis of characteristic band positions, shapes, and intensities in the infrared (IR) spectrum, see e.g. BH Günzler, H.-U. Gremlich, IR Spectroscopy, 4th edition, Wiley-VCH GmbH & Co. KGaA, Weinheim, 2003; G. Socrates, Infrared and Raman Characteristic Group Frequencies: Tables and Charts, third edition, John Wiley & Sons, 2004; RM Silverstein, FX Webster, DJ Kiemle, Spectrometric Identification of Organic Compounds, John Wiley & Sons, Inc., 2005; J. Liu, Y. Hou, S. Gao, M. Ji, R. Hu, Q. Shi, J. Therm. Anal. Calorim. 1999, 58, 323-330; M. Pedersen, HD Ashmead, US6518240 (B1) 2003; JJ-C. Ko, SX-J. Xie, EP2204099 (A1) 2010. Preferably, this analysis is performed using the known technique of attenuated total reflection, thus as ATR-IR.This method allows for the direct measurement of a sample without any sample preparation and thus without contamination with auxiliary substances (for example, potassium bromide in the case of conventional sample preparation as a KBr pellet), which in turn could influence the measurement, e.g., by reducing the measurement resolution through band broadening or distorting the band shape (Christiansen effect). The latter undesirable effect, which is due to excessively coarse particle size, does not occur with the product material manufactured according to the invention, since it exists as compact particles in the small single-digit micrometer range with a comparatively large surface area ( ). Figure 2a , d ).

[0102] The structural characterization of, for example, zinc bismethionate can be found in RB Wilson, P. de Meester, and DJ Hodgson, Inorg. Chem. 1977, 16, 1498-1502, and in M. Rombach, M. Gelinky, and H. Vahrenkamp, ​​Inorg. Chim. Acta 2002, 334, 25-33. In the present case, such spectroscopic reference measurements have also demonstrated that the products prepared according to the invention correspond to wet-chemically obtained reference material, some of which is commercially available. This is particularly noteworthy because the American Association of Feed Control Officials (AAFCO) defines such chelates as products of the reaction of a metal ion of a soluble metal salt with an amino acid (see, for example, SD Ashmead and M. Pedersen, US6426424 (B1) 2002).Specifically, the chelation process according to the invention is demonstrated by significant changes in the IR spectrum, which will be explained below using suitable examples. ATR-IR analysis, spectroscopic proof of chelate formation

[0103] In the course of IR analysis for the purpose of proving chelation during the execution of the process according to the invention, the change in position of the nitrogen-hydrogen stretching vibration NH of the ammonium group is of particular importance. This band is represented by approximately 3150 wavenumbers (cm⁻¹ < , abscissa unit of the IR spectrum) in the case of the amino acid glycine ( Figure 3 ) or from below 2950 cm -1< in the case of methionine ( Figure 4 ) through chelation to approximately 3440 cm -1< in zinc glycinate ( Figure 5 ) or approximately 3295 cm⁻¹ in zinc methionate ( Figure 6) shifted. The resulting wavenumber differences prove the involvement of the nitrogen center in the complexation, thus the chelation itself. Further bands in this region above 3000 cm⁻¹ are essentially due to the presence of water of crystallization. In addition, overtones of intense fundamental vibrations of the upper fingerprint region can be found there. The originally present asymmetric carboxylate stretching vibration v as (COO -< ) of the amino acids appears at approximately 1575 cm⁻¹. It hardly changes its position during chelation. The symmetric counterpart of the carboxylate vibration v sym (COO -< ) also remains positionally stable. Nevertheless, the formation of a chelate during the reaction according to the invention is clearly recognizable even in this upper fingerprint region, since a deformation vibration δ sym (NH 3 +< ) around 1500 cm⁻¹ is detected only in the case of the free amino acid (e.g.δ sym (NH 3 +< , Glycine): 1498 cm -1< , δ sym (NH 3 +< , Methionine): 1514 cm -1< , δ sym (NH 3 +< , Lysine): 1511 cm -1< ), which, however, disappears during the reaction milling and chelation. The respective metal-nitrogen vibration in these chelates is found at only low wavenumbers in the lower fingerprint region due to the relatively high atomic masses of the metals, e.g., Met-N (zinc methionate) at 419 cm -1< . The significant changes in the IR spectrum of the metal chelates compared to the corresponding spectra of the free amino acids also clearly demonstrate the chelation during the process according to the invention.

[0104] In the case of copper bisglycinate, signals around 3330, 3260 and 3160 cm⁻¹ are found in the IR range of the chelate bands compared to the starting material glycine (compare Figure 7 ). Summary of the advantages of the invention

[0105] The invention provides an energy-efficient, solvent-free process according to claim 1 for the production of amino acid metal chelates. Energy savings compared to previous processes result, firstly, from the fact that no wet chemical reactions with subsequent drying are required. Although a mechanochemical reaction is carried out, no grinding media or additional masses, such as balancing masses in eccentric vibratory mills, are required as is otherwise the case in the prior art. The process product is thus kept free of metal abrasion from the grinding media. Preferably, a pressureless mixture of the starting materials amino / hydroxycarboxylic acid and metal oxide, metal carbonate, or metal oxalate is fed into a fluidized bed counterjet mill and mechanochemically converted to the corresponding metal chelate solely by the fluid jet (gas jet) through particle collisions initiated by the gas flow.Furthermore, the energy efficiency results from the fact that the process according to the invention operates solely through the milling gas jet, without the need for any additional input of thermal energy, radiant energy, or similar sources. This novel, autogenous reaction process for the complete chemical conversion of the starting materials allows the combination of organic acids, preferably naturally occurring amino acids such as glycine, methionine, or lysine, with oxides, carbonates, or oxalates of trace element metals, in particular zinc, copper, manganese, selenium, iron, calcium, magnesium, nickel, cobalt, vanadium, chromium, or molybdenum. In this way, sought-after feed additives or dietary supplements are obtained, e.g., zinc (bis)glycinate, zinc (bis)methionate, zinc (bis)lysinate, copper (bis)glycinate, copper (bis)methionate, copper (bis)lysinate, and many others.The equally possible use of hydroxycarboxylic acids instead of amino acids leads primarily to food additives; other (industrial) uses of such chelate compounds are known. The process product is structurally homogeneous and very pure. Thermal stress or decomposition of the organic chelating ligand, especially the amino acids, is avoided, as are contaminations from mill and grinding media abrasion.

[0106] Unlike known methods using different mills, such as eccentric vibrating mills, the fluidized bed counterjet mill also operates continuously.

[0107] The reaction water is removed with the escaping grinding gas without any separate energy expenditure. Reference symbol list

[0108] 10 Fluidized bed counterjet mill 1 Grinding chamber 2 Feed line 3 Material reservoir 4 Fluid nozzle (grinding gas nozzle) 5 Fluidized bed (reaction chamber)

Claims

1. Process for the production of amino acid- or hydroxycarboxylic acid-metal-chelates, in which a solvent-free mixture of at least one metal compound from the group consisting of metal oxide, metal hydroxide and metal salt, and at least one solid organic acid, which comprises at least one chelating acid from the group of alpha- and beta-amino acids and hydroxycarboxylic acids, is subjected to intensive mechanical stress, characterized in that the reaction partners metal compound and organic acid are introduced in particulate form into a fluid jet of a fluidized bed counter-jet mill (10) operating without milling media, and in that within a reaction space formed in a jet region of the fluid jet (5) formed in a jet region of the fluid jet, at least one of the reaction partners is mechanically activated by particle collision processes and a solid-state reaction to form the metal chelate is triggered, 90% of which have a diameter of at most 15 µm and 50% of which have a diameter of at most 5 µm.

2. Method according to claim 1, characterized in that a fluidized bed is formed as a reaction chamber (5) in the fluidized bed counterjet mill in a fluid flow section in a crossing area of the jet direction of at least two fluid nozzles (4) together with the introduced particulate reaction partners.

3. Process according to claim 1, characterized in that the fluidized bed counterjet mill (10) is operated at flow velocities of 300 to 1000 m / s and a grinding gas pressure of 5 to 10 bar, preferably 7 to 8 bar.

4. Method according to one of claims 1 to 3, characterized in that the reaction partners are transported into a grinding chamber (1) by means of a conveyor device and reach the reaction chamber (5) inside the grinding chamber (1) in free fall.

5. Process according to one of claims 1 to 4, characterized in that the fluid is a gas, preferably selected from the group of gases air, nitrogen, argon, carbon dioxide, and steam, each individually or in admixture.

6. Method according to one of claims 1 to 5, characterized in that the metal compound is an inorganic metal oxide, a metal hydroxide or mixed oxide, or an inorganic or organic metal salt, preferably a metal carbonate or metal oxalate, in particular that the metal compound contains at least one metal selected from the group consisting of zinc (Zn), copper (Cu), manganese (Mn), selenium (Se), iron (Fe), calcium (Ca), magnesium (Mg), nickel (Ni), cobalt (Co), vanadium (V), chromium (Cr), and molybdenum (Mo), or in that a mixture of such metal compounds is used.

7. Amino acid- or hydroxycarboxylic acid-metal-chelate obtained by a method according to any one of claims 1 to 6.

8. Metal chelate composition containing at least one metal chelate compound with a polyvalent metal cation and at least one chelate ligand comprising at least one chelate-forming acid from the group of alpha- and beta-amino acids and hydroxycarboxylic acids, characterized in that the compound is in the form of particles with a mean particle size in the single-digit micrometer range, of which 99.9% have a diameter of at most 25 µm, of which 90% have a diameter of at most 15 µm and 50% have a diameter of at most 5 µm, and in that the metal chelate compound is free from mill and milling media abrasion, obtained by a process according to one of claims 1 to 6.

9. Metal chelate composition according to claim 8, characterized in that the stoichiometric ratio of chelating acid to metal compound in the at least one metal chelate compound is 0.5:1 (mol / mol) to 4:1 (mol / mol).

10. Metal chelate composition according to any one of claims 8 to 9, characterized in that the metal of the one or more metal chelate compounds is selected from the group consisting of zinc (Zn), copper (Cu), manganese (Mn), selenium (Se), iron (Fe), calcium (Ca), magnesium (Mg), nickel (Ni), cobalt (Co), vanadium (V), chromium (Cr), and molybdenum (Mo).

11. Metal chelate composition according to one of claims 8 to 10, characterized in that the or at least one metal chelate compound contained therein is a 2:1 amino acid metal chelate compound of zinc or copper or is a 3:1 amino acid metal chelate compound of iron or manganese.

12. Metal chelate composition according to one of claims 8 to 11, characterized in that at least one of the following metal chelate compounds is contained or the composition consists of it: zinc bisglycinate, zinc bislysinate, zinc bismethionate, copper bisglycinate, copper bislysinate, copper bismethionate, iron bisglycinate, iron trisglycinate, iron bislysinate, iron trislisinate, iron bismethionate, iron trismethionate, manganese bisglycinate, manganese trisglycinate, manganese bislysinate, manganese trislisinate, manganese bismethionate, manganese trismethionate.

13. Use of the metal chelate composition according to any of claims 8 to 12 as or in a feed additive, food, nutrient supplement, food additive, medicament, antiseptic, in a pharmaceutical composition, as or in a fermentation additive, fertilizer additive, seed treatment agent, plant protection agent, catalyst for chemical reactions, or as or in an electroplating additive.

14. Composition containing the product of the process according to any one of claims 1 to 6 or the metal chelate composition according to any one of claims 8 to 12, in the form of a feed additive, food, nutrient supplement, food additive, medicine, antiseptic, pharmaceutical composition, fermentation additive, fertilizer additive, seed treatment agent, plant protection agent, catalyst for chemical reactions, or electroplating additive.