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混和型研磨仪 Fast homogenization of small sample volumes

Mixer mills grind and homogenize small sample volumes quickly and efficiently by impact and friction. These ball mills are suitable for dry, wet and cryogenic grinding as well as for cell disruption for DNA/RNA or protein recovery. For special applications such as mechanosynthesis, they offer unique solutions. Mixer mills are well known for their ease of use and small foot-print compared to other types of ball mills.

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Mixer Mills - Function Principle

The grinding jars of mixer mills perform radial oscillations in a horizontal position. The inertia of the grinding balls causes them to impact with high energy on the sample material at the rounded ends of the jars and pulverize it. High energy milling is possible by operating at high frequencies up to 35 Hz. The movement of the jars and balls causes further size reduction effects through friction and additionally leads to effective mixing of the sample. The degree of mixing can be increased by using several smaller balls. 

Mixer Mills - Fields of application

混合球磨仪适用于干湿两种模式下对软质、硬质、脆性及纤维状物料的粉碎处理。凭借其占地面积小、操作简便及处理时间极短的特点,该设备堪称实验室中的全能型设备。
混合球磨仪特别适用于机械化学(机械合成、机械合金化及机械催化)等科研任务,或纳米级超细胶体研磨,同时也满足混合与均质化等常规需求。
该设备还广泛应用于通过珠磨法进行细胞破裂以提取DNA/RNA。可处理高达240毫升的细胞分散液,用于蛋白质提取或代谢组学分析。
混合球磨仪的核心优势在于其卓越的多功能性——部分型号可实现物料的主动冷却或加热,相比其他球磨仪能提供更精准的工艺控制。在机械化学领域,对研磨罐内反应的可控性尤为重要。
根据型号不同,可实现-196°C至100°C的温度调节。混合研磨机提供1、2或6工位配置,研磨罐与研磨球具备多种尺寸、结构及材质选择。

典型样品材料 - 氧化钛

氧化钛 
湿磨

典型样品材料

金属合金
干磨

典型样品材料: 头发

头发
干磨

典型样品材料:轮胎橡胶

轮胎橡胶
冷冻研磨 莱驰研磨仪

Mixer Mills - cooling and heating options

CryoMill 设计专用于 -196°C 的低温研磨,而 MM 500 control 的工作温度范围为 -100°C 至 +100°C,温度调节范围为 -100°C 至 0°C。

降温的好处包括, 例如:

  • 保护对温度敏感的分析物,如挥发性物质或药品和食品成分
  • 脆化无法在室温下粉碎的样品材料
  • 湿法研磨,以保持低于一定温度(在某些情况下可低于室温)
  • 机械化学反应中,停止反应并稳定中间产物,使最终产品与未冷却时的结果不同
如果在加工过程中加热样品材料,某些应用会得到改善,例如:
  • 制酱(食品工业)
  • 强化机械化学反应
所需温度和操作设置取决于具体应用。

Mixer Mills - Grinding jar and ball materials

如何选择最合适的材料?

研磨工具的材料选择需考虑后续分析需求。例如,若对样品进行重金属含量分析,钢制研钵与钢珠的磨损可能导致铬元素混入样品,从而造成分析结果失真。因此,仅有氧化锆等无金属材料适用于此类分析。
研磨工具的材质亦影响其效率,其中两大关键因素为:
能量输入(与材料密度相关)
硬度

能量输入

The higher the density of a material, the higher is the energy input. This means that the acceleration of, for example, tungsten carbide grinding balls at a given speed is higher compared to jar and ball materials of lower density. The energy input is higher when the ball hits the sample, causing a better crushing effect which is beneficial for pulverizing hard-brittle samples.
For soft materials, on the other hand, too much energy input may prevent effective crushing. In such cases, the sample is not really pulverized into a fine powder but rather forms a layer that sticks to the jar walls and covers the balls. Homogenization is not possible that way and sample recovery is difficult. That is why for soft materials other mill types, for example rotor mills, are better suited.

硬度

要找到硬度合适的罐和球材料,考虑因素很简单:材料的硬度必须高于样品的硬度。如果材料硬度较低,磨球就会被样品材料的颗粒磨碎。

不同材料的研磨工具

不建议使用不同材料的配件。例如钢制研磨罐搭配氧化铵材质的研磨球,首先,两种材料的磨损都会影响分析结果,其次,会加速配件的磨损。

Mixer Mills - Jar types and sizes

经典型混合研磨仪采用螺旋紧固研磨瓶,专为小样本量的快速处理和粉碎而设计。研磨瓶材质涵盖硬化钢、不锈钢、碳化钨、玛瑙、氧化锆及聚四氟乙烯。
MM 500 nano与MM 500 control型号采用螺纹锁紧研磨罐。此类罐体可承受高达5bar压力,安全顶盖确保操作便捷。新型罐体设计特别适用于湿法研磨及纤维状样品(如毛发)的粉碎处理。
平盖设计可充分利用额定容积,例如研磨纤维样品时,或确保湿法研磨中物料、微球与液体达到最佳混合状态。
可选材质包括淬火钢、不锈钢、碳化钨及氧化锆,确保加工过程无污染。所有研磨罐尺寸和材质均可配备通气盖,适用于惰性气氛下的加工操作。

Screw-top jars
Screw-lock jars

1. Screw-top jar
2. Screw-lock jar 
3. Filling volume

Screw-top jars MM 400, MM 500 vario, CryoMill Screw-lock jars MM 500 nano, MM 500 control
不同的研磨罐材质 7 (4) 4
研磨罐尺寸 1.5 | 5 | 10 | 25 | 35 | 50 ml 50 | 80 | 125 ml
Aeration lids
GrindControl
Integrated safety closure
适用于干磨
Suitable for wet grinding Limited - jar design is not optimal for applying the 60% filling rule Yes, designed to apply the 60% rule
纤维样品研磨 Yes, very easy handling, as the lids are flat and the full volume of the jar can be used to fill in voluminous sample

Mixer Mills - Recommended jar fillings

用于干磨

干磨时,通常采用所谓的三分之一规则来获得最佳效果。也就是说,大约三分之一的罐子容积应该装满研磨球。根据这一规则,球越小,就越需要装满三分之一的罐子。另外三分之一的罐子容积应装满样品材料。

根据这一规则,既能提供所需的粉碎能量,又能在罐中装入足够的样品材料以防止磨损;

用于干磨

1.三分之一的自由空间
2.

用于含纤维的样品

对于纤维材料或粉碎后体积急剧下降的材料,建议使用较高的样品填充量。罐中需要有足够的材料以减少磨损。如有必要,可以在几分钟后添加更多材料,以保持所需的最小体积;

用于含纤维的样品

1.三分之二的样品
2.

用于湿磨

要生产粒度小至 100 纳米或更小的颗粒,需要湿磨和摩擦,而不是冲击。要做到这一点,需要使用许多表面大、摩擦点多的小球。因此,干法研磨工艺中推荐的三分之一填充量被 60% 规则所取代,即 60% 的罐子中填充小球。样品量应约为 30%。首先将小球加入罐中(按重量计!),然后加入材料并混合。最后仔细混合分散剂液体。

用于湿磨

1.六分之一到三分之一的样品 + 液体
2. 三分之二的研磨球

如何选择合适的研磨球尺寸

为确保研磨球能快速粉碎样品,其尺寸应至少为最大样品块的三倍。通常可采用约1000倍的系数来确定目标最终细度所需的合适球体尺寸。若目标研磨粒度为30微米(D90),则直径20毫米至30毫米的研磨球最为适宜。若需更细颗粒,则需采用较小研磨球进行二次研磨工序。
由于较大研磨球可能压碎较小球体,不建议在单次研磨过程中混合使用不同尺寸的研磨球。

Wet and Nanoscale grinding in mixer mills

Nanotechnology deals with particles in a range from 1 to 100 nm. These particles possess special properties due to their size, as their surface is greatly enlarged in relation to their volume (so-called “size-induced functionalities”). Ultrafine particles are, for example, harder and more break-resistant than larger particles.

Small particles tend to get charged on their surfaces and agglomerate during dry grinding, which is a limiting factor for size reduction. For nanoscale grinding, liquid or dispersant is used to keep the particles separated and salt solutions help to neutralize the surface charges. Long chain molecules in the liquid can keep the particles separated thanks to steric hindrance.  

Aeration lids from RETSCH

通气顶盖经过专门设计,旨在提升实验室研磨过程的效率与安全性。在处理需控制环境的物料时(如湿法研磨或操作活性物质),其优势尤为显著。此时可通过氮气等惰性气体冲洗研磨罐,置换瓶内包括氧气在内的环境气体。 通气顶盖具还支持将气体直接注入研磨罐,这对特定化学反应或维持惰性环境至关重要。研磨罐可承受高达5bar的压力,有助于在研磨过程中促进气体分子融入反应体系。 此外,通气顶盖可使研磨罐直接连接至分析仪——既可在行星式球磨机(或Emax设备)运行后连接,亦可在MM 500 nano或MM 500 control运行过程中连接。此配置便于分析研磨过程中释放的气体或化学反应产生的气体。盖体配备多种不同材质内衬——如不锈钢、氧化锆和碳化钨——使同一顶盖可适配不同研磨罐类型。

混和型研磨仪 - 常见问题

What is a mixer mill?

Mixer mills belong to the family of ball mills and are characterized by their small footprint, fast processing times and great versatility.

They are used for mixing, pulverizing and homogenizing hard, medium-hard, brittle, soft, elastic and fibrous sample materials.

Size reduction is effected through impact and friction. Mixer mills from Retsch are available with one, two or six grinding stations.

Which applications require a mixer mill?

混合球磨仪可在数秒内完成小样本体积的干式、湿式及低温粉碎,为纳米级研磨提供所需能量输入。
其典型应用领域包括通过珠磨法破裂细胞以提取DNA/RNA和蛋白质。
混合球磨仪在机械化学领域亦被广泛应用,尤其配备冷却与加热功能的机型。

How does a mixer mill work?

Sample material and grinding balls are filled into the jar which is clamped into the mill. The radial oscillations performed by the mill lead to the pulverization by impact and friction of the balls. The sample is also thoroughly mixed by the movements of jar and balls.