Spiral jet mill with multiple product injector nozzles and method for grinding granular products

Abstract

A spiral jet mill for grinding granular products, such as TiO2 particles, comprises a plurality of product injector nozzles, for example, at least two, for injecting a corresponding number of flows of steam or other pressurized gas and granular products into the grinding chamber while mixing them. In use, to achieve energy savings with respect to the amount of steam or other pressurized gas used per unit of granular product being ground, the ratio of the total amount of pressurized gas, for example, the sum of all input steam and grinding steam injected into the grinding chamber, to the granular product, such as TiO2 pigment particles, is preferably smaller than the corresponding ratio used in conventional processes.

Description

Technical Field

[0001] Background A spiral jet mill is used to grind granular materials, such as powder materials, to reduce the particle size of the granular materials. Conventional spiral jet mills generally include a planar circular grinding chamber, which is surrounded by a manifold equipped with a plurality of grinding steam injectors for injecting grinding steam into the grinding chamber. Generally, each grinding steam injector is oriented at the same angle in the radial direction, i.e., tangentially with respect to the center line, so as to promote a relatively uniform flow around the grinding chamber in a clockwise or counterclockwise direction. The lid covers the upper end of the grinding chamber and includes a single product injector nozzle used to inject the flow of the mixed input steam and granular product into the grinding chamber. The product injector nozzle is generally oriented at an acute angle tangentially with respect to the center line and horizontally so as to inject the flow of the product and the input steam along the same clockwise or counterclockwise direction as the grinding steam. When the granular particles swirl on the outer peripheral side of the grinding chamber, they collide with the grinding steam and finally grind the granular particles. The smaller ground particles finally move to the center of the grinding chamber, where the discharge outlet allows the ground particles to be discharged from the grinding chamber by the discharge steam. An example of a conventional spiral jet mill can be found in U.S. Patent No. 7,150,421.

[0002] Spiral jet mills that rely on steam as the input gas and / or grinding gas may use a large amount of steam, and thus energy, to grind a given amount of granular product. Therefore, it is desirable to improve the efficiency of conventional spiral jet mills in order to reduce the input costs and / or have a lower carbon footprint and be more environmentally friendly.

[0003] Summary of the Invention In one embodiment of the invention, the spiral jet mill includes a manifold surrounding and at least partially defining a grinding chamber; a grinding gas injector port extending through the manifold into the grinding chamber for injecting grinding material into the grinding chamber; a cover covering the manifold and at least partially defining the grinding chamber; and a discharge port for discharging the grinding product from the grinding chamber. A first product injector nozzle is directed into the grinding chamber and configured to inject a first flow of input gas and granular product into the grinding chamber while mixing them; and a second product injector nozzle is directed into the grinding chamber to inject a second flow of input gas and granular product into the grinding chamber while mixing them.

[0004] One or more of the product injector nozzles may extend through the cover. For example, the first product injector nozzle may extend through the lid, and the second injector nozzle may extend through another part of the spiral jet mill, for example, through the bottom wall of the grinding chamber and / or through the manifold. Preferably, at least each of the first and second product injector nozzles extends through the cover. Optional additional product injector nozzles may similarly extend through the lid or through another part of the spiral jet mill, insofar as they are configured to inject a flow of product into the grinding chamber where grinding by the grinding material takes place.

[0005] In some optional configurations, the spiral jet mill may have three or more product injector nozzles. For example, the spiral jet mill may optionally have a third product injector nozzle extending through a cover to inject a third flow of vapor and granular product into the grinding chamber while mixing them. In other optional configurations, the spiral jet mill may have four, five, six, seven, eight, or in fact any number of product injector nozzles that can be fitted within the available physical space.

[0006] The product injector nozzles may be oriented in any manner suitable for injecting the product into the grinding chamber to enable grinding of the product. Several optional configurations are described below. For example, one or all of the product injector nozzles may be oriented tangentially to the centerline of the grinding chamber and offset from the centerline of the grinding chamber. One or more of the product injector nozzles may be oriented to inject each flow in the same clockwise or counterclockwise direction around the grinding chamber. The first and second product injector nozzles may be located on opposite sides of the centerline, for example, along the centerline and on the same diameter.

[0007] The product injector nozzles may be oriented in parallel sets, for example, in parallel pairs. For example, the first product injector nozzle may be oriented parallel to the second product injector nozzle in parallel vertical planes equidistant from the centerline of the grinding chamber and on opposite sides of the centerline of the grinding chamber. If there are four, six or other pairs of product injector nozzles, two or more pairs may be oriented parallel to each other in parallel vertical planes, for example, with each pair offset by a predetermined angle from one or more other pairs along the perimeter of the grinding chamber.

[0008] One or more of the product injector nozzles may have an injection end positioned within the grinding chamber to directly inject the product into the grinding chamber. In some configurations, the injection ends of two or more product injector nozzles may be positioned at the same radial distance from the centerline.

[0009] The manifold may take any form suitable for injecting the grinding material into the grinding chamber. For example, the manifold may have multiple grinding gas injector ports extending through the manifold into the grinding chamber for injecting the grinding material into the grinding chamber. In some configurations, the manifold may have 1 to 30 grinding gas injector ports, but any number that can be physically fitted to the manifold can be used. Preferably, some or all of the grinding gas injector ports are oriented tangentially rather than radially through a centerline, thereby causing the gas and product in the grinding chamber to vortex in a single direction, either clockwise or counterclockwise. In some configurations, all grinding gas injector ports and product injector nozzles may be tangentially oriented in the same clockwise or counterclockwise direction overall to promote a uniform circumferential flow of gas and product in the grinding chamber. However, in other configurations, one or more of the grinding gas injector ports and product injector nozzles may be oriented in other directions, for example, opposite directions in the clockwise / counterclockwise directions, radially, or tangentially to different radial circles or other arcs, in order to increase turbulence in the grinding chamber and / or promote different flow patterns.

[0010] The product injector nozzle may take any suitable form for injecting a flow of a mixture of the product to be pulverized and a pressurized gas. In some configurations, one or more of the product injector nozzles may have a primary inlet port for the gas and product and one or more secondary inlet ports for adding one or more metered feed substances or other materials to the flow. In one example, the primary and secondary inlet ports may converge in a mixing chamber and / or be otherwise connected to a mixing chamber, where the product from the secondary inlet port is mixed with the flow of the product and pressurized feed gas. The passage may extend from the mixing chamber into the grinding chamber to inject the mixed flow into the grinding chamber. However, the provision of secondary inlet ports is not mandatory and may be omitted, or any number of secondary inlet ports may be provided.

[0011] Another aspect of the present invention provides a method for grinding a granular product using a steam jet mill disclosed herein. This method includes the steps of simultaneously injecting a first flow of a mixture of input gas and granular product into a grinding chamber through a first product injector nozzle and a second flow of the same mixture into the grinding chamber through a second product injector nozzle. The grinding material is injected into the grinding chamber through a grinding gas injector port, thereby colliding with the granular product from the first and second flows to grind the granular product into smaller particles.

[0012] A spiral jet mill can be operated with virtually any type of pressurized gas, such as steam, air, nitrogen, or similar gases, or combinations thereof. Preferably, the pressurized gas is inert and / or flammable, but depending on the application, flammable or other reactive gases may be used. In some configurations, the input gas and / or grinding material may be, or contain, pressurized gases such as steam, air, and / or nitrogen.

[0013] A spiral jet mill can be used to grind and reduce the particle size of granular materials of almost any substance. For example, the granular product may be, and / or contain, TiO2 (titanium dioxide) pigment particles having a particle size of about 0.1 μm to 5 cm. However, other types of granular products and / or particle sizes may be ground in a spiral jet mill.

[0014] The ratio of pressurized gas to granular material can be selected to enhance grinding capacity and / or energy efficiency. In some exemplary configurations, the ratio of input gas (e.g., input steam) to granular material (e.g., TiO2 pigment particles) in the first and second flows may be less than about 2:1, more preferably about 1.1:1 to about 1.9:1, and even more preferably about 1.5:1. For example, in some configurations, the ratio of input gas to granular material in the flow may be about 1.54:1, but other ratios are also conceivable.

[0015] In several configurations and methods, the spiral jet mill and / or method of the present invention can provide a more efficient system for reducing the particle size of granular materials compared to known spiral jet mills having only a single product injection nozzle. Other advantages, uses, and / or characteristics will become apparent from the detailed description and drawings below. [Brief explanation of the drawing]

[0016] [Figure 1] This is a side view of a spiral jet mill according to a particular embodiment of the present invention, with the cover shown in cross-section. [Figure 2] This is a plan view of the spiral jet mill showing the cover. [Figure 3] Figure 2 is a detailed cross-sectional view of the product injector nozzle of the cover along line AB.

[0017] Detailed explanation The following description is intended to illustrate the things shown in the drawings and / or the various hypothetical embodiments shown and / or relating to the things shown in the drawings. Any feature illustrated and / or described in relation to one embodiment can be combined with any one or more features illustrated and / or described in relation to another embodiment. Any dimensions shown in the drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0018] Referring here to the drawings, Figures 1-3 show the lid of an exemplary spiral jet mill 10 according to a particular non-limiting aspect of the present invention. The spiral jet mill 10 comprises a mill body 12 and a cover 14. The mill body 12 includes a manifold 16 that surrounds and defines the outer circumference of a grinding chamber 18. In this example, the manifold 16 has a generally planar circular shape, which defines a circular grinding chamber 18 with respect to a centerline 19 defined in this example by a vertical central axis, and has a height defined by the height of the manifold along the vertical central axis, and a diameter extending across the grinding chamber through the vertical central axis. Other shapes of the mill body 12 and manifold 16 are also possible, and the shape is not limited to a circular shape.

[0019] At least one, in this example twelve, grinding gas injector ports 20 extend through the manifold 16 to allow injection of grinding material, such as steam or other compressed gas, into the grinding chamber 18. The manifold 16 may have more than twelve grinding gas injector ports 20, or fewer than twelve gas injector ports. In another example, the manifold 16 has six grinding gas injector ports 20. Preferably, the grinding gas injector ports 20 are uniformly spaced at an angle around the periphery of the manifold 16. The grinding gas injector ports 20 are oriented tangentially with respect to the central axis to promote circumferential flow of gas and particulate matter in the grinding chamber 18 in a single direction. In this example, each of the 12 grinding gas injector ports 20 is oriented at an angle of approximately 10° to approximately 20° (e.g., approximately 15°) from the radial direction to promote gas flow in a counterclockwise direction when viewed from above, but other orientations, e.g., other angles, different angles between the various grinding gas injector ports 20, and / or orientations to promote flow in clockwise and / or counterclockwise directions may be implemented. The mill body 12 may have other features, e.g., other grinding gas inlets, grinding gas outlets, bottom walls, and / or additional features of any type suitable for directing the grinding gas into the grinding chamber 18 and / or discharging the grinding gas.

[0020] The cover 14 is positioned on the upper surface of the mill body 12 so as to cover and surround the grinding chamber 18. Thus, the cover 14 defines, at least partially, the upper surface of the grinding chamber 18. The cover 14 is preferably removably attached to the mill body 12 by, for example, bolts 22 or other types of fasteners in the operating position as shown in Figure 1. Other mechanisms are also possible for attaching the cover 14 to the mill body 12 so as to surround the grinding chamber 18. In this example, the cover 14 has the shape of a generally planar disc with a stepped outer shoulder that is complementary to the stepped inner shoulder on the upper surface of the mill body 12. The cover 14 may have other shapes, such as a dome, a cylindrical end, or other shapes, configured to facilitate the flow of gas and product within the grinding chamber 18 in a desired manner.

[0021] Unlike conventional spiral grinding mills, the spiral jet mill 10 includes at least two product injector nozzles 24, e.g., a first product injector nozzle 24a and a second product injector nozzle 24b, configured to inject a stream of compressed gas, e.g., steam, and granular product, e.g., titanium dioxide (TiO2) pigment particles, into the grinding chamber 18. In this example, the first and second product injector nozzles 24 are supported by a cover 14 and extend through the cover 14. However, in other examples, one or more of the product injector nozzles 24 may extend through other parts of the spiral jet mill 10, e.g., through the floor of the grinding chamber 18 and / or through the side walls of the grinding chamber, e.g., through the manifold 16. As best seen in Figure 3, each product injector nozzle 24 extends downward at an acute angle to the horizontal plane of the cover 14 into the grinding chamber 18 (as can be seen in the drawing).

[0022] As best seen in Figure 2, each product injector nozzle 24 is oriented tangentially to the central axis of the grinding chamber 18 at a predetermined angle from its radius. Thus, each tangentially oriented product injector nozzle 24 is offset from the central axis of the grinding chamber 18 and oriented to inject first and second flows, respectively, in the same clockwise or counterclockwise direction around the grinding chamber. Preferably, each product injector nozzle 24 is offset by the same distance from the central axis, however, the product injector nozzles 24 may be offset by different distances and / or oriented at different angles and / or in different directions with respect to the central axis. In other configurations, one or more of the product injector nozzles 24 may be oriented in different directions, for example radially, in different clockwise or counterclockwise directions, and with or without different offsets from the central axis, in order to facilitate fluid flow and / or particle collisions in different patterns within the grinding chamber 18.

[0023] The first and second product injector nozzles 24a and 24b are arranged and oriented to form a pair of parallel product injector nozzles 24 that are oriented along parallel planes on opposite sides of the central vertical axis, each facing in opposite directions and offset on opposite sides of the central vertical axis, thereby injecting the respective flows of granular product and compressed gas in a counterclockwise direction, similar to the grinding gas injector port 20.

[0024] The spiral jet mill 10 may have three or more product injector nozzles 24. For example, there may be three, four, or almost any number of product injector nozzles 24, and the only practical limitation is the physical space available for mounting the product injector nozzles through the cover 14 and / or other locations through the mill body 12.

[0025] As can be best seen in FIG. 3, each product injector nozzle 24 may include a primary inlet port 26 for gas and product, and a secondary inlet port 28 for the metered feed material. The secondary inlet port 28 may be in the form of a smaller nipple and may be used for metering feed, for example, of other liquids such as silicone oil, trimethylpropane, etc. to provide a so-called organic coating of the particles that takes place during grinding in the grinder. The primary inlet port 26 and the secondary inlet port 28 converge in a mixing chamber 30 that can mix the flow of compressed gas and particulate product with any metered feed material for which mixing into this flow is desired. However, the secondary inlet port 28 may be omitted and / or other ports may be provided. The passage 32 extending from the mixing chamber 30 into the grinding chamber 18 directs the flow directly into the grinding chamber 18 through the injection end 34 of the product injector nozzle 24 disposed within the grinding chamber and below the cover 14.

[0026] Although the first and second product injector nozzles 24a and 24b in this example are shown to be substantially identical, it is envisioned that any one or more of the product injector nozzles 24 may not be identical to each other but may be configured to supply different products and / or additive materials into the grinding chamber 18, respectively.

[0027] The discharge port 36 enables the pulverized particulate matter to be discharged from the pulverization chamber 18. In this example, as shown in FIG. 1, when the cover 14 is operably attached to the mill body 12, the discharge port 36 extends upward through the cover 14 and is aligned with the central axis of the pulverization chamber. The discharge port 36 has a generally cylindrical tube section that is oriented substantially vertically in the operating position and extends through the cover 14, although other configurations, shapes and / or positions of the discharge port 36 may be used. For example, the discharge port 36 may also or alternatively extend downward through the bottom wall of the pulverization chamber 18. The discharge port 36 is preferably aligned with the central vertical axis, whereby smaller particles move radially inward and are finally discharged from the pulverization chamber 18 through the discharge port 36.

[0028] The spiral jet mill 10 can be used to pulverize particulate products, such as TiO2 pigment particles and / or other particulate products, by simultaneously injecting a first stream of a mixture of feed gas and particulate product into the pulverization chamber 18 through the first product injector nozzle 24a and a second stream of a mixture of feed gas and particulate product into the pulverization chamber through the second product injector nozzle 24b. Also, the comminution material is injected into the pulverization chamber 18 through the comminution gas injector port, thereby colliding with the particulate product from the first and second streams to pulverize the particulate product to a smaller particle size. The comminution material is preferably a pressurized gas, such as steam, air, and / or nitrogen, although other compressed gases and / or other comminution materials, such as hard comminution particles, may be used or included. The feed gas is preferably steam, although other compressed gases may be used or included. Preferably, the first and second streams of feed gas and particulate product, and the comminution material are all injected into the pulverization chamber simultaneously, although this is not strictly essential.

[0029] The ratio of the total amount of gas injected (e.g., input steam + grinding steam) to the granular product (e.g., TiO2 pigment particles) may be within a wide range. For example, the ratio of the total amount of gas injected to the granular product may be about 0.1:1 to 10:1, preferably about 0.2:1 to 5:1, and more preferably about 0.5:1 to 3:1. In one preferred method, the ratio of the total amount of gas injected (e.g., input steam + grinding steam) to the granular product (e.g., TiO2 pigment particles) is about 1.5:1, for example, 1.54:1, and the input gas is about 54% of the total amount of gas injected into the grinding chamber per unit time (i.e., input gas + grinding gas). As can be seen from the examples detailed below, this total gas-to-TiO2 pigment input ratio (approximately 1.5:1) results in an energy input saving of approximately 23% compared to conventional TiO2 jet milling techniques using a total gas-to-TiO2 pigment input ratio of 2:1. However, the method and apparatus are not limited to these specific ranges, as it is expected that the energy efficiency and processing capacity advantages of the multi-entry micronizer (spiral jet mill) disclosed herein can be realized over a wider range. In fact, the greater the actual or standard ratio (total vapor:product) when there is only one inlet, the greater the advantages. For example, if a conventional spiral jet mill with only one inlet (i.e., one product injector) has a ratio of 5:1, using a new spiral jet mill with twice the number of inlets (i.e., two product injectors) allows the new spiral jet mill to reduce the ratio of total steam input to total product input by approximately 25%, resulting in a ratio of 3.75:1 and a steam saving of 1.25 tons per ton of product. In contrast, for a conventional (single product injector) spiral jet mill using a total steam:product ratio of 2:1 for grinding TiO2 pigment particles, the same 25% reduction with a spiral jet mill equipped with two product injectors results in a total steam:product ratio of 1.5, and a steam saving of 0.5 tons per ton of product.For other types of granular products to be ground, the conventional ratio of the total amount of gas introduced to the total amount of granular product introduced may differ from that in the case of TiO2 particles. However, with the use of multiple nozzles to reduce the conventional total vapor:product ratio, even lower ratios are possible according to the concepts described herein.

[0030] As shown below, the use of a spiral jet mill with two (or more) nozzles according to specific embodiments of the present invention can result in significant energy savings in the grinding of TiO2 pigments for use in various end products. In the following examples, the energy consumption required to grind the granular product, which in these examples is TiO2 pigment particles, consists mainly of input steam and grinding steam. When one or more additional product injection nozzles are supplied to the mill instead of the single product injection nozzle of a conventional mill, and the input of grinding steam is kept constant, it is possible to save the required energy. Compared to a mill with only one product injection nozzle, there is a greater solid charge. That is, there are more particles per unit volume in the grinding chamber 18, which increases the probability of particle-particle collisions and, consequently, leads to more efficient grinding. In addition, the total volumetric flow rate of the granular product and input gas is increased by the additional charge, which increases the velocity within the grinding chamber and, consequently, enhances the grinding effect. The increased radial velocity also increases the selectivity of the statically visible process, which prevents coarse material from being discharged from the mill.

[0031] Next, we will describe some non-limiting examples of studies that demonstrate the specific, but not necessarily all, potential applications of the above principle.

[0032] Baseline Example 1: The first baseline comparative example considers a conventional method using a conventional spiral jet mill having a single product injection nozzle and 14 grinding nozzles. The spiral jet mill is operated at a processing rate of 4 tons per hour of granular product to be ground (TiO2 pigment particles in this example) with a total steam volume to pigment ratio of 2:1, and the input steam accounts for 54% of the total input steam and grinding steam, i.e., 4320 kg / hour of input steam and 3680 kg / hour of grinding steam, distributed across the 14 grinding nozzles. (Note: All tons in this example and the following examples are metric tons = 1000 kg).

[0033] Example 2: In a second example according to a particular aspect of the present invention, a spiral jet mill is considered that has two product input nozzles and 14 grinding nozzles (as described above herein). With twice the input volume of TiO2 pigment particles (granular product to be ground) and steam input, i.e., 8 tons / hour of product, and the total of steam input and grinding steam with steam input being 54%, 2 × 4320 kg / hour of steam input = 8640 kg / hour of steam, and 8 tons / hour of pigment plus 1 × 3680 kg / hour of steam grinding steam is supplied (total steam input of 12,320 kg / hour). In this example, an energy saving of 3680 kg / hour of steam is achieved. In this example, the ratio of total steam to pigment is 1.54:1 (not 2:1), which corresponds to a 23% energy saving and a simultaneous 100% increase in the processing capacity of granular product to be ground (e.g., pigment) in a direct comparison with baseline Example 1.

[0034] Baseline Example 3: In the third baseline comparative example, a conventional spiral jet mill with one product injection nozzle and six grinding nozzles is used. 130 kg / h of pigment, 140 kg / h of input steam, and 120 kg / h of grinding steam distributed across the six grinding nozzles are injected into the spiral jet mill. The ratio of total steam to pigment is 2 tons of steam per ton of pigment (i.e., 2:1).

[0035] Example 4: In a fourth example according to a particular aspect of the present invention, a spiral jet mill is used, which has two product injection nozzles and six grinding nozzles (as described above herein). Twice the amount of pigment and steam input is used, i.e., 2 × 130 kg / h = 260 kg / h of product, 2 × 140 kg / h of steam input, plus 1 × 120 kg / h of steam for grinding = 400 kg / h of total steam processing. In this example, an energy saving of 120 kg / h of steam is achieved, and the ratio of total steam to pigment is 1.54:1 (instead of 2:1). This corresponds to a 23% energy saving and a 100% increase in simultaneous processing capacity compared to baseline Example 3.

[0036] These examples demonstrate that spiral jet mills equipped with two or more product injection nozzles offer significant energy savings compared to conventional grinders and can increase product processing capacity to previously unimaginable levels. Therefore, spiral jet mills and the operation of such mills according to specific embodiments of the present invention can also provide better energy efficiency for grinding TiO2 pigment particles and other granular products.

Claims

1. A spiral jet mill (10), A manifold (16) surrounds and at least partially defines the grinding chamber (18), A grinding gas injector port (20) extending into the grinding chamber through the manifold for injecting grinding material into the grinding chamber, A cover (14) that covers the manifold, and which defines at least partially the grinding chamber, A discharge port (36) for discharging the pulverized product from the pulverizing chamber, A first product injector nozzle (24a) is directed towards the grinding chamber and configured to inject a first flow of the input gas and granular product into the grinding chamber while mixing them, In a spiral jet mill (10) equipped with, The steam jet mill is A spiral jet mill (10) is further characterized by comprising a second product injector nozzle (24b) directed into the grinding chamber for injecting a second flow of the input gas and the granular product into the grinding chamber while mixing them.

2. The spiral jet mill (10) according to claim 1, wherein at least one of the first and second product injector nozzles (24a, 24b) extends through the cover (14).

3. The spiral jet mill (10) according to claim 1 or 2, wherein each of the first and second product injector nozzles (24a, 24b) extends through the cover (14).

4. The spiral jet mill according to any one of claims 1 to 3, wherein each of the first product injector nozzle (24a) and the second product injector nozzle (24b) is oriented tangentially with respect to the center line (19) of the grinding chamber (18) and offset from the center line (19).

5. The spiral jet mill according to any one of claims 1 to 4, wherein each of the first product injector nozzle (24a) and the second product injector nozzle (24b) is directed to inject the first and second flows, respectively, in the same clockwise or counterclockwise direction surrounding the grinding chamber (18).

6. The spiral jet mill according to any one of claims 1 to 5, wherein the first product injector nozzle (24a) is oriented parallel to the second product injector nozzle (24b).

7. The spiral jet mill according to any one of claims 1 to 6, wherein the first product injector nozzle (24a) and the second product injector nozzle (24b) are arranged on opposite sides of the center line (19).

8. The spiral jet mill according to any one of claims 1 to 7, wherein each of the first product injector nozzle (24a) and the second product injector nozzle (24b) has an injection end (34) in the grinding chamber (18), and the injection ends of each of the first product injector nozzle and the second product injector nozzle are located at the same radial distance from the center line (19).

9. The spiral jet mill according to any one of claims 1 to 8, further comprising a third product injector (24) nozzle directed into the grinding chamber (18), configured to inject a third flow of input gas and the granular product into the grinding chamber while mixing them.

10. A method for grinding a granular product using a spiral jet mill according to any one of claims 1 to 9, The steps include simultaneously injecting a first flow of a mixture of input gas and granular product into the grinding chamber (18) through the first product injector nozzle (24a) and injecting a second flow of a mixture of input gas and granular product into the grinding chamber through the second product injector nozzle (24b), The steps include: injecting the grinding material into the grinding chamber through the grinding gas injector port (20), thereby causing it to collide with the granular products from the first and second flows, grinding the granular products and reducing their particle size; and Methods that include...

11. The method according to claim 10, wherein the input gas includes input steam.

12. The method according to claim 10 or 11, wherein the granular product comprises TiO2 pigment particles.

13. The method according to any one of claims 10 to 12, wherein the pulverizing material includes a pressurized gas.

14. The method according to any one of claims 10 to 13, wherein the pressurized gas comprises at least one of grinding steam, air, and / or nitrogen.

15. The method according to any one of claims 10 to 14, wherein the first and second flows and the grinding material have a ratio of approximately 0.1:1 to 10:1 between the total amount of input gas and grinding material and the granular product.

16. The method according to any one of claims 10 to 15, wherein the granular product comprises TiO2 pigment particles, the input gas comprises vapor, and the grinding material comprises vapor, and the first and second flows and the grinding material have a ratio of total vapor amount to TiO2 pigment particles of less than about 2:1.

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