Systems and methods for direct oxide production - Patents.com

Abstract

The present invention provides compositions and methods for improved lead oxide production, particularly simplified and more cost-effective lead oxide production equipment and raw materials for lead oxide production. [Solution] In a ball mill or Barton pot type process, lead oxide particles are produced from a lead product formed in an electrolytic process that continuously produces metallic lead. The lead product may be in the form of lead flakes, sponge lead, or nano- and / or microcrystalline lead matrix obtained directly from the electrolytic process, optionally washed and compressed before being fed to the ball mill or Barton pot type process. Notably, the lead oxide particles so produced have the desired purity and size distribution, despite the presence of residual aqueous solutions from the electrolytic process that produces the raw material for the ball mill or Barton pot.

Description

[Technical field]

[0001] This application claims priority to our pending U.S. Provisional Application No. 63 / 140,562, filed January 22, 2021, which is incorporated herein by reference.

[0002] The field of the invention is the production of lead oxide for use in lead-acid batteries, and in particular, relates to systems and methods for the production of lead oxide from high purity lead in a micro- or nano-porous mixed matrix. [Background technology]

[0003] The background description includes information that may be useful in understanding the present invention. No admission is made that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0004] All publications and patent applications in this specification are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. In the event that a definition or usage of a term in an incorporated reference is inconsistent or contradictory with a definition of the term provided herein, the definition of the term provided herein applies and the definition of the term in the reference does not apply.

[0005] In a typical manufacturing process for producing lead acid batteries, a battery paste containing lead oxide is applied to a lead grid for formation of the active mass. Notably, despite the conceptually simple process of lead oxide formation, only two methods are currently employed for the commercial scale production of lead oxide. For example, as described in UK Patent GB 1,072,923, the oxidation of metallic lead in solid form using a grinding mill (e.g., a ball mill) where the newly formed lead oxide is dislodged from the metallic lead feed material and separated by a forced air stream. Because lead oxidation is an exothermic reaction, the mill temperature must be tightly controlled to obtain the defined product specifications and to avoid melting of the lead feed. In addition, many other operating parameters, such as feed particle size, loading rate, amplitude / rotation speed, etc., must be closely monitored / controlled as they significantly affect the product composition. Most typically, the lead oxide so produced usually contains 60-65% by weight α-PbO, the remainder being unreacted metallic lead.

[0006] Most ball mills producing lead oxide (also known as lead suboxide or grey lead oxide, having the chemical formula 2PbO.Pb) include a front end with a lead melting furnace in which lead ingots obtained from a lead smelting operation are melted. The molten lead is then cast into smaller objects, typically having cylindrical, hemispherical or spherical geometries, before being subjected to the ball mill. In other plants, larger lead ingots from a front-stage casting operation may be cut into smaller sizes before being subjected to the ball mill. As will be readily appreciated, such pre-treatment consumes energy and time, and often produces additional undesirable waste products.

[0007] Alternatively, metallic lead can also be oxidized in liquid form in a process known as the Barton pot process. Here, high purity lead is first melted in a separate vessel and then pumped into a reaction pot. The molten lead is rapidly stirred under a forced air stream, and the lead droplets formed by the stirring are partially oxidized to lead oxide (PbO), which is carried by the air stream to a collection system. The lead oxide so produced is a mixture of mainly tetragonal (α-PbO) and orthorhombic lead oxide (β-PbO), with some unreacted metallic lead. By varying the process parameters, the percentage of lead oxide can be adjusted to vary, typically between 65 and 80% by weight.

[0008] For example, US Patents US 3,322,496 and US 3,244,563 teach the Barton pot process, in which molten lead is stirred against a septum in the presence of a forced air flow to produce lead oxide, which is removed from the top space of the pot. Although such processes overcome at least some of the challenges associated with the ball mill process, various difficulties remain. In particular, the overall production rate of lead oxide is typically lower than the ball mill process, and requires a significant amount of energy. Furthermore, temperature control remains important to maintain the desired product specifications. As described in US Application US2019 / 0217390, to avoid at least some of the problems associated with the conventional Barton pot process, a continuous production reaction vessel can be employed, in which a laminar flow or atomized spray of molten lead is oxidized in a heated reaction section.

[0009] It must be understood that regardless of the oxidation method, the feed material to the process is required to be a high purity lead feedstock, usually greater than 99.9% pure. The feedstock can be modified with various elements, such as calcium (as described in US application US2006 / 0039852), or magnesium and optionally silver (as described in US patent US6,664,003 and WO02 / 071511), but it is widely understood that the purity of the lead feedstock, excluding functional additives, is very important to obtain lead oxide in the desired yield. Furthermore, temperature changes in both processes are detrimental to the product quality and composition, and impurities in the feedstock that can result in temperature changes often lead to off-specification products. As a result, most Barton pot processes require high purity lead ingots as feedstock, thus increasing costs and energy requirements. Summary of the Invention [Problem to be solved by the invention]

[0010] Thus, while various systems and methods for producing lead oxide are known in the art, all or nearly all of them have certain drawbacks. Thus, there remains a need for improved compositions and methods for producing lead oxide, particularly those relating to the provision of simplified and more cost-effective feedstocks for lead oxide production and lead oxide production equipment. [Means for solving the problem]

[0011] Summary of the Invention The subject matter of the invention is directed to various systems and methods for the production of lead oxide particles from sources other than high purity lead sources, such as high purity lead ingots. To that end, the inventors have unexpectedly discovered that lead oxide particles can be consistently produced directly from electrochemically produced lead flakes, sponge lead, and / or nano- and / or microcrystalline lead matrices, with the desired purity and size distribution, without the need for melting and ingotization. Advantageously, the process contemplated herein provides significant savings in energy consumption and time, since the output of a lead-producing electrolytic cell can be used directly (typically after compression into a solid fuel (briquette)) as input for a ball mill or Barton pot type oxidation process.

[0012] In one aspect of the inventive subject matter, we contemplate a method for producing lead suboxide comprising producing metallic lead from an aqueous lead-containing electrolyte at the cathode of an electrolytic reactor, the metallic lead being formed in the form of lead flakes, sponge-like lead, or nano- and / or microcrystalline lead matrix, and the metallic lead comprising some aqueous lead ion-containing electrolyte. Such a method comprises collecting metallic lead from the electrolytic reactor and removing a portion of the aqueous electrolyte from the metallic lead to form a lead feedstock, and further comprises feeding the lead feedstock to an oxidizer and operating the oxidizer under conditions to form lead suboxide in particulate form. In such a method, the lead suboxide comprises a plurality of lead oxide particles and a plurality of metallic lead particles having a size and composition suitable for use in a lead-acid battery active material. Contemplated methods further comprise removing at least some of the lead suboxide from the oxidizer.

[0013] In some embodiments, the metallic lead is removed from one portion of the cathode while additional metallic lead is formed from the lead ion-containing electrolyte in another portion of the cathode and / or the cathode moves relative to the lead ion-containing electrolyte. Most typically, the portion of the aqueous electrolyte is removed from the metallic lead by replacing the aqueous electrolyte with water and / or by compressing the metallic lead.

[0014] It is further contemplated that the oxidizer is a ball mill or a Barton pot, such that the lead suboxide comprises 20-40% metallic lead particles and 60-80% lead oxide particles, and / or the metallic lead particles and the lead oxide particles have an average particle size of about 0.1-10 microns.

[0015] The present inventors subsequently contemplate a method for producing lead suboxide, the method comprising the steps of producing metallic lead from an aqueous lead ion-containing electrolyte at the cathode of an electrolytic reactor, where the metallic lead is produced in the form of lead flakes, sponge-like lead, or nano- and / or micro-crystalline lead matrix, and the metallic lead comprises some of the aqueous lead ion-containing electrolyte. In another step, a portion of the aqueous electrolyte is removed from the metallic lead, thereby forming a lead feedstock for a ball mill, and in yet another step, the lead feedstock is introduced into the ball mill, and the ball mill is operated at a temperature and for a time to form lead suboxide, where the lead suboxide comprises a plurality of lead oxide particles and a plurality of metallic lead particles. Finally, at least some of the lead suboxide is removed from the ball mill.

[0016] In some embodiments, the cathode moves relative to the electrolyte and / or the electrolyte moves relative to the cathode. Most typically, the metallic lead is removed from the cathode during the movement of the cathode or the movement of the electrolyte. It is further contemplated that the step of removing the portion of the aqueous electrolyte from the metallic lead includes washing the metallic lead with water and / or compressing the metallic lead. In a typical example, the aqueous lead ion-containing electrolyte is an acidic electrolyte including an organic acid and / or an inorganic salt. Furthermore, it is preferred that the ball mill is operated to produce a composition including 20-40% metallic lead particles and 60-80% lead oxide particles, and / or the ball milling step produces a composition including a plurality of lead and lead oxide particles having an average particle size of about 0.1-10 microns. Of note, the lead raw material contains residual electrolyte or water from the washing step when it is introduced into the ball mill.

[0017] The inventors further contemplate a method of producing lead suboxide, the method comprising the steps of forming metallic lead from an aqueous lead ion containing electrolyte at a cathode of an electrolytic reactor, the metallic lead being formed in the form of lead flakes, sponge-like lead, or nano- and / or micro-crystalline lead matrix, and the metallic lead comprising some of the aqueous lead ion containing electrolyte. In another step, at least a portion of the aqueous electrolyte is removed from the metallic lead to form a lead feedstock for ball milling, and the lead feedstock is melted to form a liquid lead feedstock (having a temperature of at least 650° F.). In yet another step, at least a portion of the liquid lead feedstock is oxidized in a Barton pot process to form lead suboxide, the lead suboxide comprising a plurality of lead oxide particles and a plurality of metallic lead particles. Finally, at least some of the lead oxide particles are removed from the Barton pot process.

[0018] In some embodiments, the cathode moves relative to the electrolyte and / or the electrolyte is moved relative to the cathode, and the metallic lead is removed from the cathode during the movement of the cathode or the movement of the electrolyte. It is further contemplated that removing at least a portion of the aqueous electrolyte from the metallic lead includes washing the metallic lead with water and / or compressing the metallic lead. Most typically, the aqueous lead ion-containing electrolyte is an acidic electrolyte comprising an organic acid or an inorganic salt.

[0019] Preferably, the ball mill is operated to produce a composition comprising 20-40% metallic lead particles and 60-80% lead oxide particles, and / or the ball milling process produces a composition comprising a plurality of lead and lead oxide particles having an average particle size of about 0.1-10 microns. Most typically, but not necessarily, the lead source comprises 0.5-5% by weight of the aqueous solution. Effect of the Invention

[0020] Various objects, features, aspects and advantages of the present subject matter will become more apparent from the following detailed description of preferred embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Detailed Description The present inventors have unexpectedly discovered that lead suboxide suitable for the manufacture of lead acid battery pastes can be prepared from the output material of an electrochemical lead ion reduction process without the need for melting and ingotizing the output material. This discovery was particularly unexpected because conventional industry wisdom has generally required that the lead feedstock for ball mill or Barton pot type processes be of very high purity.

[0022] In contrast, the output materials used by the inventors were typically flaked, spongy lead, or nano- and / or microcrystalline lead matrices that were compressed into briquettes and even contained significant amounts of electrolyte and / or water. Indeed, lead oxide produced in the Ball Mill or Barton process consistently had the desired chemical composition and size, even in the presence of sulfur-containing acids, such as methanesulfonic acid, in the electrolyte or water in the output material.

[0023] In one exemplary embodiment, metallic lead is produced electrochemically in a continuous process in which a rotating cathode is partially immersed in a lead ion-containing acidic electrolyte, lead is reduced on the immersed cathode portion, and metallic lead is removed from the non-immersed portion of the cathode. Most typically, the electrolyte is an aqueous solution of methanesulfonic acid, and the rotating cathode is typically made of aluminum.

[0024] In such a process, metallic lead is recovered from the cathode in the form of a micro- and / or nano-porous mixed matrix in which the metallic lead has micro- and / or nanometer-sized structures (typically acicular / wire-like / dendritic / dendrite) that trap a portion of the electrolytic processing solvent and some molecular hydrogen (i.e., H), some of which is expelled upon compression under the matrix's own weight. Most notably, such matrices had a black appearance and very low bulk density. Indeed, in some embodiments, the matrix floated on the solvent and was found to have a bulk density of less than 1 g / cm. 3When the matrix is ​​compressed or other force is applied, the density increases (e.g., 1-3 g / cm 3 Or 3~5g / cm 3 or more) and a metallic silver-like luster appears. In another embodiment, the mixed matrix is ​​removed from the cathode (e.g., wiped or scraped off) and has a density of 3-5 g / cm 3 , 5~7g / cm 3 , 7~9g / cm 3 Viewed from a different perspective, it should be appreciated that the mixed matrix contains metallic lead in high purity (e.g., at least 99.9%, or at least 99.99%, or at least 99.999%, or at least 99.9999%), along with molecular hydrogen and residual electrolyte.

[0025] In the most typical process of forming the mixed matrix, the reduced lead ions do not form an adhesive film on the cathode and can be easily removed from the cathode by simply moving the cathode relative to the electrolyte, vibrating the cathode, or wiping the cathode with a material to which lead can adhere (e.g., plastic, lead film, etc.). Thus, lead recovery can be continuous. Particularly when rotating or reciprocating electrodes are employed, lead ions can be reduced on one part of the electrode or electrode assembly while metallic lead can be simultaneously recovered from another part of the electrode or electrode assembly. In another example, lead can be removed from the cathode by vibrating the cathode or spraying a fluid over the cathode. Exemplary contemplated systems, methods, and apparatus for generating the mixed matrix used in the process according to the inventive subject matter are described in U.S. Pat. Nos. 9,837,689 and 10,340,561, both of which are incorporated herein by reference.

[0026] In yet another embodiment, metallic lead can also be produced in an electrochemical process from a typically aqueous electrolyte, as described in International Publication WO2019 / 171282. Here, the electrolyte is typically an aqueous ammonium chloride solution, and the electrodes are often placed in an electrochemical flow-through cell. To remove metallic lead, typically in the form of lead flakes, the cathode may be subjected to ultrasonic treatment, electrolyte injection, and / or cathode movement. The metallic lead thus removed can then be used in a direct oxidation process as a feedstock to a ball mill or Barton pot oxidation device.

[0027] Once the lead flakes, sponge lead, or mixed matrix are produced, the lead material is typically subjected to a compaction process to remove at least a portion of the trapped electrolyte and optionally hydrogen, and the material is preferably subjected to a solidification process to produce a lead solid fuel with reduced electrolyte and / or moisture content. In an alternative aspect, compaction can be performed using a gravity-driven filter press or the like as a drainage process. As will be readily understood, the electrochemically produced metallic lead can be subjected to a washing step to remove at least a portion of the acid or other components and / or to wash in one or more alloying metals, such as magnesium, calcium, silver, etc., prior to solidification. In the most typical embodiment, the compacted lead material is then used directly as a feedstock for a ball mill or Barton pot type process.

[0028] As will be readily understood, the lead material may be compressed to remove at least some of the electrolyte or other solvent that may be present. For example, if the lead material is obtained from an aqua-refining process, the compression may remove at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95% of the electrolyte or other solvent. It should also be noted that, if desired, the lead material may be washed with water or other solvent to remove residual electrolyte and / or other undesirable components. Compression can be performed in many ways known in the art. For example, compression can be performed using a filter press, a roller press, and / or a solid fuel method (briquetting). Additionally, compression is also used to achieve a form factor suitable for ball milling, and all forms, sizes and shapes currently used for ball milling are considered suitable for use herein. For example, contemplated shapes include cylinders, spheres, hemispheres, pellets, regular shapes, and irregular shapes. Furthermore, it should be noted that the compacted lead can have a weight suitable for any ball mill, for example between 100g and 1000g, or between 300g and 3000g, or between 600g and 6000g, or between 1000g and 10000g, or even between 10000g and 50000g or more.

[0029] Ball milling may then be performed using conventional equipment and processes well known in the art. Most typically, the ball milling process produces a composition comprising 20-40% metallic lead and 60-80% lead suboxide, and / or a plurality of lead and lead suboxide particles having an average particle size of about 0.1-10 microns. Of course, it should be appreciated that the ball milling process can be adjusted to provide different product specifications and compositions using adjustments known in the art (e.g., temperature, oxidizing gas flow, material residence time, etc.). Furthermore, it should be noted that the ball mill may be an existing ball mill from which the melting and recasting modules can be removed, or a new installation that is supplied with lead feed material (e.g., produced in an aqua refining process). Thus, it should be appreciated that the ball mill may be located with the lead material production or may be located at a remote location (e.g., at least 1 mile, or at least 5 miles, or at least 10 miles, or at least 50 miles, or at least 100 miles).

[0030] The preferred Barton pot type process uses the compressed lead material in molten form, typically at a temperature of at least 650 degrees Fahrenheit. Other suitable options for the Barton pot type process include those in which the liquid lead feedstock is sprayed into an oxygen-containing atmosphere, as described in, for example, U.S. Patent Application US2019 / 0217390, and those in which the liquid lead feedstock is stirred in the presence of an oxygen-containing air stream, as described in U.S. Patent No. 3,332,496, both of which are incorporated herein by reference. As will be readily understood, the Barton pot type process contemplated herein can also produce metallic lead particles, depending on the particular operating conditions set for a particular Barton pot type process. Most typically, at least a portion of the lead oxide particles (and any metallic lead particles present and / or desired) are removed from the process for further use, and most typically for lead acid battery paste production. In other words, the Barton pot process can produce lead suboxide, which includes lead oxide particles and metallic lead particles.

[0031] In this context, it should be recognized that, contrary to conventional wisdom, the use of relatively heterogeneous / impure feedstock and especially lead feedstock including metallic lead and aqueous solutions, such as water, or aqueous electrolytes including sulfur-containing acids (e.g., alkanesulfonic acid, sulfuric acid, sulfamic acid, etc.), and / or inorganic salts, at a given content of lead oxide particles, is still acceptable for the consistent production of lead oxide particles with the desired size distribution and purity. Without wishing to be limited by a particular theory or hypothesis, the inventors believe that residual sulfur compounds burn off as SO2, SO3, CO2 when melted to form liquid feedstock for the Barton Pot process, and that the residual sulfur compounds react with lead to form PbSO4 and PbS, which are oxidized by O2 generated from the water in the feedstock. Furthermore, hydrogen in the feedstock can easily react to H2S and H2O, both of which can further react with metallic lead to form lead oxide and PbS, which are then oxidized to lead oxide. Similar reactions are believed to occur where lead feedstock undergoes an exothermic process in a ball mill. In this manner, impurities and contamination that would otherwise lead to process instability are advantageously driven off without significantly affecting the product purity and size distribution of the lead oxide particles.

[0032] With regard to suitable lead sources, it is understood that the lead source does not necessarily have to be prepared as described above, but all electrochemical and redox-based chemical methods are considered suitable for use herein, as long as such source is not in the form of a solid metallic lead deposit (such as may be obtained by electrorefining methods). Thus, and from another perspective, the lead source includes at least some solvent, e.g., aqueous solution, non-aqueous solution, and / or electrolyte. From another perspective, contemplated sources include all metallic lead, including materials prepared in lead manufacturing processes other than smelting or ingotization. Thus, the source includes aqueous electrolytes, which may be acidic (e.g., including acids such as carboxylic acids, sulfuric acids, sulfamic acids, alkanesulfonic acids, fluoboric acids, etc.) or basic (e.g., including sodium or potassium hydroxide, sodium carbonate, etc.) electrolytes, organic and / or inorganic salts, non-aqueous or molten salt electrolytes, and / or water.

[0033] For example, the residual (aqueous) solution may be present in the lead raw material in an amount of at least 0.1% by weight, or 0.2% by weight, or at least 0.3% by weight, or at least 0.4% by weight, or at least 0.5% by weight, or at least 1% by weight, or at least 1.5% by weight, or at least 2.5% by weight, or at least 3.5% by weight, or at least 5% by weight, or at least 7% by weight, or at least 10% by weight. That is, the residual (aqueous) solution may be present in the lead raw material in an amount of 0.1-0.5% by weight, or 0.5-1.0% by weight, or 1.0-2.5% by weight, or 2.5-5.0% by weight, or 5.0-7.5% by weight, or 5.0-10% by weight. Depending on the type of residual (aqueous) solution, the solution may contain salt, acid, and / or basic components, typically in amounts of 0.01-0.1%, or 0.05-0.5%, or 0.5-2.5%, or 2.5-5%, or 5-10%, or 10-20%, or 15-35%, or 25-50%, or even higher. Thus, the salt, acid, and / or basic components are present in the solution in an amount of at least 5%, or at least 10%, or at least 20%, or at least 30% by weight.

[0034] The purity of metallic lead in the lead source is typically at least 98%, at least 99%, more preferably at least 99.9%, or at least 99.99%, or at least 99.999%, or at least 99.9999%. However, it should be understood that the lead source may also be doped with one or more metals to improve oxidation, with particularly preferred metals including calcium, magnesium, and silver.

[0035] It is understood that depending on the particular nature and operating parameters of the Barton pot type process or ball mill operating conditions, the process product may be only lead oxide particles or a mixture of lead oxide and metallic lead particles. Thus, various ratios of lead oxide particles to metallic lead particles are contemplated, and a suitable amount of lead oxide particles in the process product may be at least 50%, or at least 60%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or even higher. Thus, the ratio of lead oxide particles to metallic lead particles may be 99:1 to 9:1, or 95:5 to 8:2, or 9:1 to 75:25, or 8:2 to 7:3, or 8:2 to 65:35, etc.

[0036] In further contemplated aspects, the purity of the lead oxide and lead particles is generally greater than 99%. For example, the purity of the lead oxide and / or metallic lead particles is at least 99%, or at least 99.9%, or at least 99.95%, or at least 99.99%, or at least 99.995%, or even higher. In one or more embodiments, the product of the ball mill or Barton pot type process may include 0% to 100% orthorhombic lead oxide by weight. For example, the product material may include orthorhombic lead oxide in an amount of 0% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 100% by weight, or any combination thereof. In additional embodiments, the product of the ball mill or Barton pot type process may contain 0% to 100% by weight of tetragonal lead monoxide. For example, the product material may contain 0% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 100% by weight, or any combination thereof.

[0037] According to additional embodiments, the product material of the presently described ball mill or Barton pot type process may contain a mixture of tetragonal lead oxide, orthorhombic lead oxide, and metallic lead (otherwise called free lead) in all percentages from 0% to 100% by weight of any one component. A typical requirement for an active material for a lead acid battery is a mixture with tetragonal lead oxide as the major component, metallic lead as a minor component, and orthorhombic lead oxide allowed in small amounts. For example, the product may contain a mixture of tetragonal lead oxide, orthorhombic lead oxide, and metallic lead in weight percent ratios of 90:0:10, 85:0:15, 80:0:20, 75:0:25, 70:0:30, 65:0:35, 90:5:5, 85:5:10, 80:5:15, 75:5:20, 70:5:25, 65:5:30, 60:5:35, 80:15:5, 75:15:10, 70:15:15, 65:15:20, 60:15:25, 55:15:30, 50:15:35, or any other combination of the three components. However, some lead-acid battery technologies may require a mixture that contains a larger percentage of orthorhombic lead oxide. For example, the product may be a mixture of tetragonal lead oxide, orthorhombic lead oxide, and metallic lead, comprising 15% to 20% by weight, 20% to 25% by weight, 25% to 30% by weight, 30% to 35% by weight, 35% to 40% by weight, 40% to 45% by weight, 45% to 50% by weight, or any combination thereof, of orthorhombic lead oxide.

[0038] Further, it is contemplated that the size distribution of lead oxide (and metallic lead) particles produced by the ball mill or Barton pot process using the lead feedstocks presented herein will be relatively uniform and will have diameters of 1000 microns or less (e.g., 500 microns or less, 400 microns or less, 300 microns or less, 200 microns or less, 100 microns or less, 50 microns or less, 25 microns or less, or even smaller). For example, the lead oxide (and metallic lead) particles will just pass through a 50 mesh US standard sieve and thus have a diameter of 300 microns or less. For example, contemplated lead oxide (and metallic lead) particles will have a diameter of d 50The (median) diameter is 1 to 5 microns, 5 to 10 microns, 10 to 25 microns, 25 to 50 microns, 50 to 100 microns, 100 to 150 microns, 150 to 200 microns, 200 to 250 microns, 250 to 300 microns, or any combination thereof. From a different perspective, it is therefore contemplated that lead oxide particles may be prepared in which 95% by weight of the lead oxide particles have a diameter of 100 microns or less, or in which 95% by weight of the metallic lead particles have a diameter of 1000 microns or less. EXAMPLES

[0039] Aqueous lead-containing electrolyte, as a mixture of free acid and metal ion salts, with .about.25 wt.% total methanesulfonate, was pumped through an electrolytic cell operated under conditions such that elemental lead formed on a rotating cathode. Metallic lead formed as a micro- and / or nano-porous mixed matrix, containing about 40 wt.% retained electrolyte. Metallic lead was continuously removed from the moving cathode by a scraper, placed on a conveyor, and sent to a press (typically without a washing step), which squeezed about 85-90% of the entrained electrolyte out of the lead to produce a lead briquette containing about 95 wt.% solid lead and about 5 wt.% electrolyte retained in the pores of the briquette. The briquettes were air-dried for several days to several weeks (preferably within 3 days) to dry out surface moisture, but a significant amount of moisture remained within the pores and body of the briquette. The composition of the electrolyte entrained in the lead briquettes was ~25 wt% methanesulfonate, ~4 wt% dissolved lead, and ~1.3 wt% metallic impurities. Sulfur, as a component of methanesulfonic acid, accounted for approximately 8 wt% of the electrolyte.

[0040] Barton Pot Process: The briquettes were melted in a melting pot connected to a Parton pot lead oxide production process. The temperature of the melting pot was maintained at about 630-650 degrees Fahrenheit while the briquettes were melted. The dross formed from melting the briquettes was removed from the melting pot (to reduce impurity accumulation) before feeding it to a reaction pot where the molten lead was converted to oxide. The lead oxide formed was found to have a purity of at least 99.97% with less than 0.002% by weight (cumulative) of significant impurities such as Fe, Cu, Zn, Cd, As, Sn, Sb, Ni, and Bi. Most impurities were minor elements such as Na, Al, K, Ca, and Ba. Notably, no S was detected in the lead oxide produced.

[0041] It should be understood that in some embodiments, numbers expressing properties such as amounts of ingredients, concentrations, reaction conditions, and the like, used to describe and claim some embodiments of the present invention are modified by the term "about." Accordingly, in some embodiments, the numerical parameters in the specification and claims are approximations that may vary depending on the desired properties sought by a particular embodiment. The recitation of numerical ranges herein is intended to serve merely as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each separate value is incorporated into the specification as if it were individually referred to.

[0042] All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. Any and all examples provided with respect to specific embodiments herein, or illustrative language (such as "for example"), are intended merely to better illustrate the scope of the invention and do not otherwise limit the scope of the invention as claimed. No language in the specification should be construed as indicating any element essential to the practice of the invention that is not claimed.

[0043] As used throughout the description and claims of this specification, "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Also, as used in the description of this specification, "in" includes "in" and "on," unless the context clearly dictates otherwise. As used herein, and unless the context clearly dictates otherwise, the term "coupled to" is intended to include direct couplings (two elements are coupled to one another) and indirect couplings (at least one additional element is disposed between the two elements). Thus, the terms "coupled to" and "coupled with" are used interchangeably.

[0044] It will be apparent to those skilled in the art that many modifications beyond those already described are possible without departing from the inventive concept herein. The subject matter of the present invention is therefore not limited except as set forth in the claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced element, component, or step may be present, used, or combined with other elements, components, or steps not expressly referenced. When the specification or claims refer to at least one selected from the group consisting of A, B, C, and N, it should be interpreted as requiring only one element from the group, not A+N or B+N, etc.

Claims

1. A method for producing lead suboxide, producing metallic lead from an aqueous lead ion-containing electrolyte at a cathode of an electrolytic reactor, wherein the metallic lead is formed in the form of lead flakes, sponge lead, or a nano- and / or micro-crystalline lead matrix, and wherein the metallic lead comprises some of the aqueous lead ion-containing electrolyte; collecting the metallic lead from the electrolytic reactor; removing a portion of the aqueous lead ion-containing electrolyte from the metallic lead to form a lead feedstock comprising at least 1 wt. % of the aqueous lead ion-containing electrolyte, wherein the aqueous lead ion-containing electrolyte comprises impurities, and optionally the impurities comprise sulfur compounds; providing the source of lead to an oxidizer and operating the oxidizer under conditions to form lead suboxide in particulate form and to oxidize the impurities, wherein the lead suboxide comprises a plurality of lead oxide particles and a plurality of metallic lead particles having a size and composition suitable for use as a lead acid battery active material, and the lead suboxide comprises less than 0.01 wt. % impurities; and removing at least some of the lead suboxide from the oxidizer; The method includes:

2. 2. The method of claim 1, wherein said metallic lead is removed from one portion of said cathode while additional metallic lead is formed from said lead ion-containing electrolyte in another portion of said cathode.

3. 2. The method of claim 1, wherein said cathode moves relative to said lead ion-containing electrolyte.

4. 2. The method of claim 1, wherein a portion of said aqueous electrolyte is removed from said metallic lead by replacing said aqueous electrolyte with water.

5. 2. The method of claim 1, wherein said portion of said aqueous electrolyte is removed from said lead metal by compressing said lead metal.

6. 10. The process of any one of the preceding claims, wherein the oxidizer is a ball mill.

7. The process of any one of claims 1 to 5, wherein said oxidation apparatus is a Barton pot.

8. 6. The method of any one of claims 1 to 5, wherein said lead suboxide comprises 20-40% metallic lead particles and 60-80% lead oxide particles.

9. 6. The method of any one of claims 1 to 5, wherein said plurality of metallic lead particles and said lead oxide particles have an average particle size of about 0.1 to 10 microns.

10. 1. A method for producing lead suboxide, comprising the steps of: producing metallic lead from an aqueous lead ion containing electrolyte at a cathode of an electrolytic reactor, wherein the metallic lead is produced in the form of lead flakes, sponge lead, or a nano- and / or micro-crystalline lead matrix, and wherein the metallic lead comprises some of the aqueous lead ion containing electrolyte; removing a portion of the aqueous electrolyte from the metallic lead, thereby forming a lead feedstock for ball milling, the lead feedstock comprising at least 1 wt. % of the aqueous lead ion-containing electrolyte, the aqueous lead ion-containing electrolyte comprising impurities, and optionally the impurities comprising sulfur compounds; providing said lead feedstock to said ball mill and operating said ball mill at a temperature and for a time to form lead suboxide and oxidize said impurities, wherein said lead suboxide comprises a plurality of lead oxide particles and a plurality of metallic lead particles, and wherein said lead suboxide comprises less than 0.01% by weight of said impurities; and removing at least some of the lead suboxide from the ball mill; The method includes:

11. 11. The method of claim 10, wherein the cathode is moved relative to the electrolyte and / or the electrolyte is moved relative to the cathode, and the metallic lead is removed from the cathode during the movement of the cathode or the movement of the electrolyte.

12. 11. The method of claim 10, wherein removing said portion of said aqueous electrolyte from said metallic lead comprises washing said metallic lead with water and / or compressing said metallic lead.

13. 11. The method of claim 10, wherein said aqueous lead ion-containing electrolyte is an acidic electrolyte comprising an organic acid and / or an inorganic salt.

14. 11. The method of claim 10, wherein the ball mill is operated to produce a composition comprising 20-40% metallic lead particles and 60-80% lead oxide particles.

15. 11. The method of claim 10, wherein the ball milling step produces a composition comprising a plurality of lead and lead oxide particles having an average particle size of about 0.1 to 10 microns.

16. 10. The method of any one of the preceding claims, wherein the lead feedstock contains residual electrolyte or water from a washing step when fed to the ball mill.

17. 1. A method for producing lead suboxide, comprising the steps of: producing metallic lead from an aqueous lead ion-containing electrolyte at a cathode of an electrolytic reactor, wherein the metallic lead is formed in the form of lead flakes, sponge lead, or a nano- and / or micro-crystalline lead matrix, and wherein the metallic lead comprises some of the aqueous lead ion-containing electrolyte; removing at least a portion of the aqueous lead ion containing electrolyte from the metallic lead to form a lead feedstock for ball milling, the lead feedstock comprising at least 1 wt. % of the aqueous lead ion containing electrolyte, the aqueous lead ion containing electrolyte comprising impurities, and optionally the impurities comprising sulfur compounds; melting the lead feedstock to form a liquid lead feedstock; oxidizing at least a portion of the liquid lead source in a Barton pot process to form lead suboxide and to oxidize impurities, wherein the lead suboxide comprises a plurality of lead oxide particles and a plurality of metallic lead particles, and wherein the lead suboxide comprises less than 0.01% by weight of the impurities; and removing at least some of said lead oxide particles from said Barton pot process; The method includes:

18. 18. The method of claim 17, wherein the cathode is moved relative to the electrolyte and / or the electrolyte is moved relative to the cathode, and during the movement of the cathode or the movement of the electrolyte, the metallic lead is removed from the cathode.

19. 20. The method of claim 17, wherein removing at least a portion of the aqueous electrolyte from the lead metal comprises washing the lead metal with water and / or compressing the lead metal.

20. 18. The method of claim 17, wherein said aqueous lead ion-containing electrolyte is an acidic electrolyte comprising an organic acid or an inorganic salt.

21. 18. The method of claim 17, wherein the ball mill is operated to produce a composition comprising 20-40% metallic lead particles and 60-80% lead oxide particles.

22. 20. The method of claim 17, wherein the ball milling step produces a composition comprising a plurality of lead and lead oxide particles having an average particle size of about 0.1 to 10 microns.

23. 18. The method of claim 17, wherein said lead source comprises 0.5 to 5 weight percent of said aqueous solution.

24. 20. The method of claim 17, wherein the liquid lead source has a temperature of at least 650 degrees Fahrenheit.