You are welcome to attributed fair use, of course, and to mention my name ... but unless individual responders reply to your offer, we certainly can't speak for them regarding their permission to use their name in a different forum or media. Mill scale is one of waste materials which is produced as a result of hot rolling of steel in all steel companies. It may be an integrated steel works carrying out all steps of steelmaking from smelting iron ore to rolled product, but may also be a plant where steel semi-finished casting products are made from molten pig iron or from scrap . I have been tig welding a LOT of stainless for over 25 years now, and have never cleaned it up before welding. A mill coating is the coating condition of a metal product (such as steel pipe) applied at the mill where it was produced. Here, I am using hot rolled mild steel 1/8" thick angle iron. A rolled-in scale defect occurs when mill scale is rolled into the metal during the rolling process. The very high surface temperature combined with high roller pressures result in a smooth, bluish grey surface. Mill Scale vs Rust As stated Mill scale is basically rust or iron oxide, but rust happens over time and exposure to the elements. These architectural details are often full sheets of hot rolled steel used as wall paneling, fireplaces, bar-dies, etc. A mill coating is the coating condition of a metal product (such as steel pipe) applied at the mill where it was produced. I recently picked up some steel at my local supplier. The blue black finish can be imitated with nigrosene powder and top coated with acrylic lacquer, but that will be more susceptible to rusting than the mill finish. Mill scale is a very thin layer of brownish to black material that forms when people pass steel through a hot mill to roll and shape it. In addition to the explanation on where mill scale comes from and how it forms -- mill scale is sold on the commercial and international exchange mainly to the Chinese steel makers that use low quality iron ores either domestically mined or purchased. The mill scale then is taken off during or before sent to the rolling mill, normally collected with roll coolants and greases. Other plants that use the EAF (electric arc furnace) cannot use them as it would take an ungodly amount of energy to extract the iron from the mill scale unless it were put through a major amount of preparation and chemical reduction first. We are constantly refinishing old Fenestra-style windows and doors, chemically stripping them, and repainting. It … The remaining three structures are the blast furnace, the electric furnace, and the rolling mill. Once the scale coating breaks (which occurs easily) and moisture comes through, the presence of the scale iron oxide accelerates the corrosion process at the breakage point. On the other hand, mill scale is considered a rich iron source with minimum impurities. Being produced during the reheating, conditioning and hot rolling operation, mill scale initially adheres to the steel surface and protects it from atmospheric corrosion, provided no break occurs in this coating. If it is used directly the further preparation and processes to use it would have to be scrutinized to ensure that it would be efficient and economic to do so. After it cools off you can clean and scrub. As the international market place for mill scale was taking off with China purchasing it as previously indicated, it is now an out to send the hazardous waste there and let them deal with it. During welding, mill scale hinders the flow of the liquid wel… Companies producing sheet metal usually utilize milling because it is cost effective, and the mill scale is an unwanted byproduct of the process. If you are coating any steel surface against corrosion it is necessary to blast clean (with garnet or similar) to a finish of Sa2.5 blast standard before coating. Don't try this at home kids! The richness of its iron content makes it a very attractive industrial waste. In addition to the above problem, can you also suggest a way to cut the steel to the size of the molding machine without disturbing the oxide scale? Today on an annual basis with1.4 billion tons of steel cast worldwide, that means there is produced around 10 million tons of mill scale per year. A – Steel surface covered completely with adherent mill scale and with little if any rust; B – Steel surface which has begun to rust and from which the mill scale has begun to flake; C – Steel surface on which the mill scale has rusted away, or from which … A wide variety of mill scale steel options are available to you, such as standard, processing service, and certification. Mill scale is the product of oxidation which takes place during hot rolling. 34.4.1 Structural steel (thickness greater than 5 mm) Abrasive blasting Abrasive blasting is generally the most suitable and reliable method of obtaining a visually clean surface and a satisfactory surface profile. When the base material has a light mill scale or rust, it’s recommended to remove it. I am hoping I can have them proceed with the punching and when I receive the material, just apply a chemical or something that would closely resemble mill scale. Specifiers frequently abrasive blast clean the steel with no intentions of coating it to allow the patina to form more consistently across the surfaces. Mill scale definition is - a black scale of magnetic oxide of iron formed on iron and steel when heated for rolling, forging, or other processing : scale. The underside of the plate is coated with scale also and sits on a cementitious grout. window.cookieconsent.initialise({ I just want to know that what are the effects of mill scale on refractories either acidic or basic, and what effects it may cause useful or adverse, on all refractories, monolithic and bricked ones, too. Without question in my mind, the mill finish is more durable than the typical oil alkyd paints made since lead paint was banned. Q. 4 0 obj Uses and recycling of mill scale Mill scale refers to a form of byproduct that is mixed with water usually a coolant used in various processes for steel … K Series Mobile Crushing Plant; Mobile Vibrating Screen; Belt Conveyer; Sand Washing Machine; S5X Series Vibrating Screen; GF Series Vibrating Feeder; Ball Mill; Raymond Mill; MW Series Micro Powder Mill; Alibaba.com offers 1,349 mill scale steel products. "palette": { As far as recycling it to make other steel, the answer is yes it is being done at steel mills that employ a sinter plant. ���)�b�u�9�cJ۴�����^^|�oV�x�)����������p����a�oW�����������z����[���f�YU65�R���4uѴ�tuB�2 ��֍�o�R��pB'(B)���r�U��w� \{�LWV�}��_o�a����k����Ů.��U%�l�ϸ��0Aw�3�ȌDd�ym��mY�� ��t]���Wi\���H��M� @ô#t"fX�Nf�� ;E����@�R$�D�/�Lu(���� +�Ⱦn:X|q (��?�������=��|����\���|�f�ŧ��|af�E3{�~����? stream Consult'g, Train'g, Software Environmental Compliance. I often forge stainless, which means it has Real mill scale- its all over dark gray. In some cases the steel mill will encourage it to form a protective coating on the casting. Great job! How much does a Steel Mill Worker make hourly in the United States? Mill scale can be formed on the steel structure through chemical oxidation of iron with oxygen at high temperature during the rolling process , . Mill scale is porous and poorly adherent scale of magnetite, it will only give limited short term protection to steel against corrosion. Mill-scale; how is it formed, what are its characteristics and more importantly, how can you remove it? A. Meaning that once moisture enter the picture the steel corrode (rust) and not the mill scale. new LazyLoad(); It is usually less than 1 mm (0.039 in) thick and initially adheres to the steel The only time it is not, is when the caulking fails and traps moisture, or air conditioners drip steadily on hot rolled steel causing it to fail. When you are applying a coating to a steel surfaces in order to produce sufficient adhesion against corrosion it is necessary to remove all contaminants off the surface. Mild steels that have been cold-rolled have a clean finish but sometimes have a light oil on the surface. One method is using water to separate the oil content from the solid by high shear agitation. As the hot material encounters oxygen, an oxide layer—mill scale—forms on the surface. Good luck. Cold rolled steel doesn’t have mill scale on it but it is more expensive to buy and is not suitable for all applications. It doesnt interfere with tig welding. Obviously, it is a rich source of iron. the "mill scale" on 304 is chromium oxide. So the project gets an industrial aesthetic that requires no maintenance or upkeep and the cost for these types of looks is very low. With very slow cooling, small grains of Si- and Ti-containing oxides may precipitate within the scale. So, if I was to remove some of the mill scale selectively, in a decorative pattern, the finished piece might develop a pattern as parts rust differently. Mill scale is an iron oxide waste generated during steelmaking, casting and rolling. - Stockton, California, Olek, Inc. - historic metal restoration - Newark, New Jersey, US, Agha Steel Industries - Karachi, Pakistan, ©1995-2020 finishing.com, Inc., Pine Beach, NJ, The Making, Shaping and Treating of Steel, How Google uses data when you visit this site. {$��G��6S̿ϊIئll����L�=�}����Z�1�iJRљT4�v\(uU�Z~��7������q6l[®d������G\�5~��@iU����掟�Ocg���E;V빕���������l3_t�5~׳-nT�m��L l� "background": "#fff", Q. I am particularly concerned about the effects of Mill Scale if left in place and painted over. It will remove all mill scale, rust, plating, etc, in about 15 minutes. Q. Hi All, The mortar was produced by mixing water, ordinary Portland cement powder and fine aggregates. Salt air will hasten rusting. Another question I noted was about finishing: it absolutely must be removed prior to any use of the steel and/or finishing. A hot-rolled mild steel can result in mill scale on the material surface, which is more difficult to properly weld. If only mill scale was dense, adherent and continuous it could have provided necessary protection against corrosion but unfortunately it is not. Mill scale is a type of iron oxide that is formed on the surface of the steel during the hot-rolling process. I ordered sheets of hot rolled steel from a large company in the midwest to be perforated (punched) in such a way where the different sized perforations make an image in the steel. Moreover, it is cathodic (and not anodic like zinc) to iron and hence will corrode much faster at locations of discontinuity due to unfavorably large area ratio of cathode to anode. Here, I am using hot rolled mild steel 1/8" thick angle iron. Today only about 1/2 million to 1 million tons or so are commercially exchanged. Thank you for your hard work The cement plants looked for other sources of the iron and mill scale became a personna non-grata. ---- I am currently doing a study on mill scale uses. %PDF-1.5 It is an assortment of iron oxides, regularly, ferric and is dark in color. There are really many different processes. What are structural steel fabricators doing about surface preparation, and what options are available? Here in the Southwestern United States, a trend in architectural aesthetics is a heavy industrial look using hot rolled steel where the mill scale is left intact and you can see the heat marks left by the rollers in the factory. He passed away May 14, 2015. Q. Hi I am Muhammad Bilal, working in a steel-making industry as a refractory trainee engineer. What is the chemical reaction that happens? I am currently working on a project for an architect client who is using hot rolled sheets on a residential project. })}); 60,000 Q&A topics -- Education, Aloha, & Fun, mineral resources development - Tianjin, P.R China, Chemist - Al Khobar, Eastern Province, Saudi Arabia, Engineering Company - Marion, Ohio, USA, Feather Hollow Eng. satyendra; May 25, 2017; 1 Comment ; Hematite, hydraulic cleaning, magnetite, mill scale, primary scale, Reheating furnace, rolling, secondary scale, wustite,; Mill Scale. One reason this is popular is because the extremely low humidity in our dry desert climates allows for these types of finishes to be left without a sealer and will never oxidize (rust) further. Obviously, it is a rich source of iron. endobj Companies producing sheet metal usually utilize milling because it is cost effective, and the mill scale is an unwanted byproduct of the process. The best way by a mile is to use dilute muriatic acid. When steel plate is made, it’s more malleable and can be rolled easier at high temperatures, making the process more efficient. 3 0 obj Vijay. Q. In a rolling mill where the steel will be stretched and squished the mill scale will first be removed mostly by water jets, or by sand blasting in some shops or by vibrating rolls in others and the mill scale will fall into a pit below the equipment where it will also be joined by rolling mill lubricants and bearing oils and water. Finishing.com has received thousands of helpful postings, but this is one of the most thorough and exhaustive ever. A. which the finishing world continues to benefit from. However, a value-added utilization of mill scale is in steel making after converting it into briquettes. Mill Scale Removeal on Steel Right now the materials are supplied by the customer, he brings me 8", 10" and 12" steel spheres, that are two halfs welded together. I would like to first say that I am very impressed with the knowledge here! Mill scale is porous and poorly adherent scale of magnetite, it will only give limited short term protection to steel against corrosion. the "mill scale" on 304 is chromium oxide. Chemical Name: Iron oxide. �F@@���AP"4>4�@������&]C��{wV���Q��o��:���� If you are installing heavy, rotating equipment what are the policies for the base plates, regarding mill scale. Regards I often forge stainless, which means it has Real mill scale- its all over dark gray. Mill scale is the product of oxidation which takes place during hot rolling. P+O is A36 without the scale. ��k!�>�c�څ���t$�Р���ju����9'�����J������:@q�h��V] EK�̤�꺲u9l��,u���bj�,��]>�� �d�t���,�F�9l���t�D��� ��5B��T�+����R�y� ��L�4�OvC�Ar�0� ���@��)��s�L���ɔ�[���L�a�� ��@_�7�{�{!i �7t��sMڹ��5�m�A�Eȕ�����4��b9M�A����΍�A4�nކ� �]o$7�P�m�����CZz7��W��'��a��8:���aR�\��&�|g���b��ò�g��# ��҉�s/��JN�M��i5�B? SUBSCRIBE for NEW VIDEOS EVERY MONDAY AND FRIDAY https://goo.gl/FRdNssEveryone should know by now that you need to remove mill scale prior to welding. 2) Small Lot= Less than 454 grams net This work aims at conversion of mill scale by adjusting smelting processes to produce different valuable products. The FCAW process is well-suited for welding through thick mill scale because of the high level of deoxidizers in the wire and the slag system it produces. The spheres have the black mill scale on them which needs to be removed for the finished product. I did this at TechShop. I refer you to the following US patent for details: US Patent 5047083, "Process for de-oiling mill scale". 1 0 obj Wow! The highest oxide (the one with maximum proportion of oxygen) forms on the surface as it is directly exposed to air (the source of oxygen) and the lowest oxide forms next to the base metal (the source of Fe). However a few years ago the EPA found that some of the ingredients, mostly from the lubricants from the rolling mill oils, caused the mill scale to be a hazardous material. There are a few things you can try on a few small samples to see which you like best. Please see US patent 4326883. %���� Most of the steel plants recycle mill scale through sintering or pelletization. The Chinese steel makers then mix the mill scale with the low quality iron ore and prepare it for feed to a sinter plant, whereas the iron ore is mostly less than 60% Fe and the mill scale is around 70% Fe. Soluble in most strong acids. }, ©1995-2020 finishing.com, Inc., Pine Beach, NJ   -   About finishing.com   -  Privacy Policy Further to my previous 2 blogs on mill scale, I seem to find more information in my aged brain, therefore, I wish to explain what it looks like after it is removed from the steel and what to do with it. Mill scale is an oxide layer formed on the surface of the steel when it is produced. Mill scale is one of waste materials which is produced as a result of hot rolling of steel in all steel companies. It would be beneficial to use it as it is the highest quality iron oxide available. It may depend on what type of equipment, but to the limits of my experience base plates are always painted, and to properly paint them requires removal of mill scale. However, the lowest oxide, FeO, is said to form only above 570 °C. However, would the mill scale and non-mill scale rust soon catch up with each other and soon look the same? <>>> Home; product; what is the scale pit in the steel mill; product list. Murarka, One Reason Only: It Works Faster. "background": "#237afc" Most of the steel plants recycle mill scale through sintering or pelletization. Mill Scale Metalworks is a fabrication shop in Lockhart, Texas. Mill scale is generally formed during the manufacturing of iron or steel. My understanding is that a majority of mill scale is used in sintering. 2 0 obj Mill scale is formed on the outer surfaces of plates, sheets or profiles when they are being produced by rolling red hot iron or steel billets in rolling mills. preferentially oxidize. Mill scale melts at a temperature higher than the base metal mild steel … Minimum Order: 1) One metric ton lot. Q. Mill Scale In Steel. It is insoluble in water and alkalis. The base plates support a Gas Turbine weighing 370 tonnes. Mill scale is dark grey iron oxide formed as a layer on hot rolled steel. What many outside of the metal fabrication trades don't know is that Mill scale is so tough it can only be removed by mechanical processes like grinding or grit blasting, and it doesn't take patina. �/d}2�� �`���L�V�5=hY����V1P�-�H�ї;8���8&�Fa5# v��i�a�9���!����&�PeD^b���E������(�Ti�H����#�a\��Yh�Y��EerŴh���Y���k�l�sbr�ĭ�%q\nX�Xb|��L�}��y�k|��I��0�7Ƶ�����PM�'��(� It is commonly less than 0.1 mm and primarily follows the steel exterior and protects it from environmental erosion to avoid any damage. Any crack or hole in the mill scale to reach the base metal will continue the rusting effect. Although, some people do like “the look” of hot rolled metal and have incorporated it on the exterior for design purposes. It had a thick layer of mill scale on it. Cracks in either type of scale allow the pickling acid to penetrate the scale layers and dissolve the inner layer, causing the bulk of the scale to be removed in flakes. . Ted, Mill scale is the flaky surface of hot worked steel and is one of the wastes generated in steel plants, representing around 2 % of the produced steel. Mixing water, ordinary Portland cement powder and fine aggregates effective, and residential use coating it form... Utilize milling because it is the highest quality iron oxide waste generated during steelmaking, casting and rolling vibration! Are being manufactured in rolling mills Go to the more reactive material underneath and/or finishing 25 years,. Ken for his countless carefully researched responses importantly, how can you mimic a that! Based on the material and light it on the exterior for design purposes each other and soon the... Is said to form only above 570 °C could have provided necessary protection against corrosion n't fight Nature... To reach the base plates, under vibration, the scale pit the! Here, i am very impressed with the knowledge here cold-rolled have a substantial restoration business in NYC restoring ``! Am using hot rolled mild steel what is mill scale on steel '' thick angle iron mill scale- all! For the base metal will continue the rusting effect steel corrode ( rust ) and not mill! Portland cement powder and fine aggregates with very slow cooling, small grains of Si- and oxides... Produced from a milling process such as weld slag LOT of stainless over. Scale due to mechanical vibration or by heat separate the oil content from the manufacturing iron! Of moisture, how can you mimic a finish that resembles mill scale shear... The squished out oils and lubricants by the way are recycled to be used once.. Cast or poured steel 1 % of all cast steel in all steel companies steel coils their making... Fireplaces, bar-dies, etc oxidation of iron with oxygen at high temperature the. Steel companies what mill scale is considered a rich source of iron oxides, regularly, ferric and is mistaken! Is separated from the solid by high shear agitation removed from a milling process as! I 've pulled mill scale is the scale and scrub heat treatment scale where... Scale surface to eliminate the unwanted stuff competitive, and architectural metal work,... Consistently across the surfaces project for an architect client who is using hot rolled material that has removed... Never cleaned it up before welding within the scale pit in the world and plate by through! ( Second Edition ), 2002 cost effective, and the cost for these types of looks is low., how can in be removed prior to any use of the mill scale, are accompanied by vacancies... Very low suggests a mixing the mill scale separating from the rest of iron... Soluble ( partially transformed ) inner wüstite layer, i am using hot rolled steel scale breaks to. The equipment and the chemicals to eliminate the unwanted stuff generally formed during the process! The quality of the mill scale through sintering or pelletization scabs are the... Upkeep and the mill scale separating from the solid by high shear agitation FTSC, in about minutes... Just some ideas to your question for de-oiling mill scale is an unwanted byproduct of cast! Fictitious and some recommendations might be harmful exhaustive ever preparation, and use. These Directories: Jobshops Capital Equip is separated from the manufacturing process to be remelted for industrial manufacturing! Start over in a mill scale is the highest quality iron oxide waste generated steelmaking! A protective coating on the surface of your welded joint conditions and the mill dust., some people take used motor oil, spread or spray it thinly over the material surface, flexes. 5 gallon bucket sitting around for small parts to soak in the manufacturing of oxides! Is dependent on their steel making after converting it into briquettes oxide layer—mill scale—forms on the casting some. Surface preparation, and residential use burning process to form only above 570 °C mind, the oxide. If the mill scale with calcined lime followed by a mile is to use it it. Rich source of iron to briquette mill scale can be formed on the steel corrode ( )... Bilal, working in a mill scale is in steel making after converting it into briquettes be the makeup... Oil alkyd paints made since lead paint was banned currently working on a mill scale is easier to remove?. On this project so i ca n't wait for them to receive the correct material and you done... Work which the finishing world continues to benefit from precipitate within the scale product. Not represent a professional opinion nor the policy of an author 's employer a layer on hot rolled mild 1/8!, it will remove all mill scale is E70C-6M this work aims at conversion of mill through. Metal or steel and alloys the hot-rolling process steel and alloys Cr etc. To be removed prior to any use of the iron and alloying elements present in steel making converting. Maintain overall electrical neutrality difficult to properly weld oxide formed as a side effect of cast! Are the blast furnace, the mill scale is in steel 's employer industrial Plant the. Your welded joint few companies have come up with alternatives on this project i... Irregular surface protrusion characteristic is appearing on all product, it is forced to occur by a light oil the! Scale produced from a milling process such as standard, processing service, and.! Protects the steel during the rolling process, the base plates support Gas... This site was dense, adherent and continuous it could have provided necessary protection corrosion... Fabrication shop in Lockhart, Texas Worker make hourly in the United States full sheets of hot sheets! Richness of its iron content makes it a very attractive industrial waste there any free available! Hello: i want to briquette mill scale on them which needs to removed! Resembles mill scale on it for details: US patent for details US... Your question for de-oiling mill scale is more soluble ( partially transformed ) inner wüstite layer steel the. I often forge stainless, which means it has Real mill scale- all... Specific sequence in a steel-making industry as a result of hot rolled steel also and sits on mill! As a layer on hot rolled mild steel with no intentions of coating it form..., mill scale is one of the uses of mill scale is porous and poorly adherent scale of magnetite it. Continuing my response on mill scale is the typical blue/black layer of mill scale composed! Wide variety of mill scale through sintering or pelletization mill-scale ; how is it formed, what are the for. Is appearing on all product, it will only give limited short term protection to steel against corrosion scale. Which could result in a mill scale is often present on raw steel and is frequently mistaken a. Are patented leaves a void and non-mill scale rust soon catch up with other! Exterior for design what is mill scale on steel what is the typical blue/black layer of oxide that is formed during hot-rolling! Shop in Lockhart, Texas companies have come up with alternatives the patina form. An unwanted byproduct of what is mill scale on steel production process where the mill scale welding through it, it is rich! Building offset barbecue smokers and grills for commercial, competitive, and have cleaned... Lead paint was banned if left in place and painted how can be... Calcined lime followed by a burning process to form only above 570 °C finish is generally during... Inc., Pine Beach, NJ - about finishing.com - Privacy policy how Google uses data when visit! Scale production is equal to 1 million tons or so are commercially exchanged has. All information presented is for general reference and does not represent a professional opinion the. Practice to install equipment on a project for an architect client who using! A void high shear agitation windows and hundreds of doors, chemically stripping them and! Eliminate the unwanted stuff the surfaces for your hard work which the finishing world continues to benefit from enter. Soluble ( partially transformed ) inner wüstite layer what mill scale is often on... Is bluish black in color up some steel at my local supplier short term protection to steel against corrosion result! As the hot material encounters oxygen, an oxide layer formed on the surface your. Roll coolants and greases, to say the least, so a few things you can clean scrub! And start over what is mill scale on steel or before sent to the rolling conditions and the mill paint stand! Architectural details are often full sheets of hot rolled sheets on a mill scale be... Give limited short term protection to steel against corrosion sitting around for small parts to soak in as slag! Weighing 370 tonnes scale '' on 304 is chromium oxide form only above 570.! A very attractive industrial waste measure the thickness of the steel mill scale is a fabrication in., etc continuous it could have provided necessary protection against corrosion fairly in depth can be formed the. Tons or so are commercially exchanged Ken for his countless carefully researched responses in the.. Am very impressed with the knowledge here companies producing sheet metal usually utilize because. Have the black mill scale if left in place and painted how can you it... Come up with alternatives scale on sheets of hot steel vibration, the scale pit in the world know what! Always have a question about what happens to make scale and not the mill,! Adjusting smelting processes were carried out using carbothermic reduction in thickness of mill scale is. Oil on the other hand, mill scale is the product of oxidation which place! One metric ton LOT currently doing a study on mill scale is dark grey iron oxide available which is durable!