product news/產品新聞
Microwave Energy May Improve Sand Reclamation 微波能改进砂再生
President of St. Paul, Minn.-based M-Wave Consult- ing Milt Mathis hopes to show the metalcasting industry microwave energy is a viable method for processing and reclaiming sand, both green and chemically bonded. Like with most new technologies, though, the burden of proof lies on the inventor. “Te problems is, until that first system is out there and doing what the industry wants it to do, it’s a tough sell,” he said. Mathis has developed a system that features a microwave-assisted rotary sand reclamation kiln. Te pro- totype processor measures 12 ft. long and 2 ft. in diameter, with an insulated processing section that is 6 ft. long and 8 in. in diameter. Materials that do not contain water, such as silica and alumina components of clay and various sands, stay relatively cool within such a processor because they are functionally transparent to microwave energy. Clay in green sand and resins, urethanes and other materials in chemically bonded sand begin to absorb microwaves at relatively low temperatures. Te M-Wave prototype features a hybrid approach that uses both thermal and microwave energy. First, the sand is heated in the rotary kiln until it reaches a point where the clay or resin will absorb microwaves. Te microwave energy then separates the clay or binding materials from the sand. Ideally, the hybrid thermal-microwave system can reduce
energy consumption, heating times and spatial require- ments. Green sand can be processed at 1,022F (550C), while chemically bonded sand can be processed around 617F (325C). Mathis only began using the M-Wave prototype with
metalcasting industry sands in November 2013. Originally intended for processing precious metal ore, the unit has not been optimized for chemically bonded and green sands. Mathis hopes this will lead to improved results, but it is still early in the process. “We’ve done a lot of lab tests and have had good results
with green sand and resin-bonded sand,” he said. “Te next step is going to be outfitting our process tube for more ther- mal character to help sand get to a little higher temperature and keep it there.” A major challenge facing the development of tech-
nology is monitoring and maintaining the temperature within the kiln. “Temperature distribution is hugely important,” he said.
“If there are significant thermal gradients within the sand bed, the sand could be processed very differently, leading to non-uniform and inconsistent results. Tat’s been a crip- pling issue for typical microwave processes. However, using our concepts, we are capable of mitigating and overcoming those uniformity issues.” Te M-Wave prototype has only been tested in a labora-
tory setting, but Mathis recently reached an agreement to run tests in a metalcasting facility, Midwest Metal Products
总部位于明尼苏达州圣保罗地区的M-Wave咨询公司 董事长Milt Mathis，希望向铸造业展示：用微波能对 湿型砂和化学粘结砂加以处理和再生是具有可行性的。 不过与大多数新技术一样，发明人需要加以证明。 “问题是，直到首套系统研制出来且符合行业的需 求，销售仍然是个大难题，”他说。Mathis已经研发出 一个微波辅助砂再生旋转炉。原型处理器长12英尺，直 径为2英尺；绝缘处理器部分长6英尺，直径为8英尺。 不含水分的材料，例如粘土和各种砂中的二氧化硅和 氧化铝，由于微波能量对它们不起作用，因此它们在这 样的处理器中处于相对冷却的状态。湿型砂中的粘土和 化学粘结砂中的树脂，氨基甲酸乙酯和其他材料在相对 低的温度开始吸收微波。 M-Wave公司样机的特点是使用热法和微波能量相结 合的混合工艺。首先，型砂在回转炉中加热，直到达到 粘土或树脂可以吸收微波能量的温度。然后，微波能量 从砂中分离粘土或粘结材料。
理论上，热法和微波相结合的系统可以降低能耗、加 热时间和对空间的要求。湿型砂可以在1,022F（550℃ ）进行处理，而化学粘结砂可以在约617F（325℃）进 行处理。 Mathis于2013年11月才开始在铸造行业推广微波样 机的使用。最初，该设备打算用于贵金属矿石的加工， 并没有针对化学粘结砂和湿型砂的再生进行优化。尽管 仍然处在研发的早期阶段，Mathis希望这项技术得到 改进。
“针对湿型砂和化学粘结砂，我们已经进行了大量的 实验室测试并取得了良好的结果，”他说，“下一步将 是提高处理器的配备，获得更多的热性能，使型砂可以 达到较高的处理温度并能够保持温度。” 技术发展的主要挑战是监控和维持窑炉内的温度。 “温度分布非常重要，”他说，“如果砂床内存在显 著的温度梯度，砂子的处理将差别很大，从而产生不均 匀且不一致的结果。这是典型的微波处理的主要问题。 但是，基于我们的设计理念，我们有能力减轻并克服不 一致的问题。”
尽管微波处理的样机只在实验室环境中测试过，但
Mathis最近与明尼苏达州威诺纳市的中西部五金制品公 司达成了在其铸造厂内试运行样机的协议。他预计样机 在夏初能被安装调试成功。
虽然在铸造厂利用微波技术的砂再生试验的成功案例 72 |
FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION September 2014
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